diff --git a/src/main/java/com/coscale/sdk/client/ApiClient.java b/src/main/java/com/coscale/sdk/client/ApiClient.java
index 257f325..a7fdad9 100755
--- a/src/main/java/com/coscale/sdk/client/ApiClient.java
+++ b/src/main/java/com/coscale/sdk/client/ApiClient.java
@@ -29,7 +29,7 @@ public class ApiClient {
     private final String APPID;
 
     /** API_PATH, API_VERSION for request URL. */
-    private final String API_PATH = "api";
+    private static final String API_PATH = "api";
     private String API_VERSION = "v1";
 
     /** URL path separator */
@@ -199,19 +199,20 @@ public int getDeserializationExceptions() {
      *            used by request.
      * @param uri
      *            of the API call.
-     * @param data
-     *            in string format to pass to the request.
+     * @param payload
+     *            data in string format to pass to the request.
+     * @param authenticate
+     *            True if the call requires authenticate, false if not.
      * @return String response for the request.
      * @throws IOException
      */
     private String doHttpRequest(String method, String uri, String payload, boolean authenticate)
             throws IOException {
-        URL url;
         HttpURLConnection conn = null;
         int responseCode = -1;
 
         try {
-            url = new URL(uri);
+            URL url = new URL(uri);
             conn = (HttpURLConnection) url.openConnection();
 
             // Set connection timeout.
@@ -288,8 +289,7 @@ private void login() throws IOException {
         String uri = credentials.usesToken() ? getAppRequestURL("/login/")
                 : getGlobalRequestURL("/users/login/");
         Credentials.TokenHelper data = call("POST", uri, credentials,
-                new TypeReference<Credentials.TokenHelper>() {
-                }, false);
+                new TokenHelperTypeReference(), false);
 
         token = data.token;
     }
@@ -328,6 +328,7 @@ public <T> T callWithAuth(String method, String endpoint, Object obj, TypeRefere
             } catch (CoscaleApiException e) {
                 if (e.statusCode == HttpURLConnection.HTTP_UNAUTHORIZED) {
                     this.token = null; // will trigger new login
+                    responseCode = 401; // 401 means login failed: https://httpstatuses.com/401
                 } else {
                     throw e;
                 }
@@ -349,6 +350,8 @@ public <T> T callWithAuth(String method, String endpoint, Object obj, TypeRefere
      *            object with data for the request. This parameter can be null.
      * @param valueType
      *            is the type expected.
+     * @param auth
+     *            true if the call requires authentication, false if not.
      * @return The Object received as a result for the request.
      * @throws IOException
      */
@@ -410,11 +413,11 @@ public String getGlobalRequestURL(String endpoint) {
     public String getRequesUrl(String endpoint, Options options, boolean globalApi) {
 
         StringBuilder sb = new StringBuilder();
-        sb.append(getBaseURL());
+        sb.append(API_BASE_URL);
         sb.append(PATH_DIV);
-        sb.append(getApiPath());
+        sb.append(API_PATH);
         sb.append(PATH_DIV);
-        sb.append(getApiVersion());
+        sb.append(API_VERSION);
         if (!globalApi) {
             sb.append(PATH_DIV);
             sb.append("app");
@@ -486,4 +489,12 @@ private <T> String objectToJson(T obj) throws IOException {
             }
         }
     }
+
+    /**
+     * Copied from the Intellij code analysis:
+     * A static inner class does not keep an implicit reference to its enclosing instance.
+     * This prevents a common cause of memory leaks and uses less memory per instance of the class.
+     */
+    private static class TokenHelperTypeReference extends TypeReference<Credentials.TokenHelper> {
+    }
 }
\ No newline at end of file
diff --git a/src/main/java/com/coscale/sdk/client/data/DataApi.java b/src/main/java/com/coscale/sdk/client/data/DataApi.java
index b3d07af..42c97ee 100755
--- a/src/main/java/com/coscale/sdk/client/data/DataApi.java
+++ b/src/main/java/com/coscale/sdk/client/data/DataApi.java
@@ -35,7 +35,14 @@ public DataApi(ApiClient api) {
      * @throws IOException
      */
     public Msg insert(String subjectId, DataInsert data) throws IOException {
-        return api.callWithAuth("POST", "/data/" + subjectId + '/', data, new TypeReference<Msg>() {
-        });
+        return api.callWithAuth("POST", "/data/" + subjectId + '/', data, new MsgTypeReference());
+    }
+
+    /**
+     * Copied from the Intellij code analysis:
+     * A static inner class does not keep an implicit reference to its enclosing instance.
+     * This prevents a common cause of memory leaks and uses less memory per instance of the class.
+     */
+    private static class MsgTypeReference extends TypeReference<Msg> {
     }
 }
diff --git a/src/main/java/com/coscale/sdk/client/events/EventsApi.java b/src/main/java/com/coscale/sdk/client/events/EventsApi.java
index a8b58f4..3f71863 100755
--- a/src/main/java/com/coscale/sdk/client/events/EventsApi.java
+++ b/src/main/java/com/coscale/sdk/client/events/EventsApi.java
@@ -39,8 +39,7 @@ public EventsApi(ApiClient api) {
      * @throws IOException
      */
     public List<Event> all() throws IOException {
-        return api.callWithAuth("GET", "/events/", null, new TypeReference<List<Event>>() {
-        });
+        return api.callWithAuth("GET", "/events/", null, new EventListTypeReference());
     }
 
     /**
@@ -54,8 +53,7 @@ public List<Event> all() throws IOException {
     public List<Event> all(Options options) throws IOException {
         String url = "/events/";
         url += (options.hasQuery() ? "?" : "&") + options.query();
-        return api.callWithAuth("GET", url, null, new TypeReference<List<Event>>() {
-        });
+        return api.callWithAuth("GET", url, null, new EventListTypeReference());
     }
 
     /**
@@ -67,8 +65,7 @@ public List<Event> all(Options options) throws IOException {
      * @throws IOException
      */
     public Event get(long id) throws IOException {
-        return api.callWithAuth("GET", "/events/" + id + '/', null, new TypeReference<Event>() {
-        });
+        return api.callWithAuth("GET", "/events/" + id + '/', null, new EventTypeReference());
     }
 
     /**
@@ -80,8 +77,7 @@ public Event get(long id) throws IOException {
      * @throws IOException
      */
     public Event insert(EventInsert event) throws IOException {
-        return api.callWithAuth("POST", "/events/", event, new TypeReference<Event>() {
-        });
+        return api.callWithAuth("POST", "/events/", event, new EventTypeReference());
     }
 
     /**
@@ -93,8 +89,7 @@ public Event insert(EventInsert event) throws IOException {
      * @throws IOException
      */
     public Msg delete(long id) throws IOException {
-        return api.callWithAuth("DELETE", "/events/" + id + '/', null, new TypeReference<Msg>() {
-        });
+        return api.callWithAuth("DELETE", "/events/" + id + '/', null, new MsgTypeReference());
     }
 
     /** Events data end point calls. */
@@ -127,8 +122,7 @@ public List<EventData> allData(Long eventId, @Nullable Long start, @Nullable Lon
             first = false;
         }
 
-        return api.callWithAuth("GET", endpoint, null, new TypeReference<List<EventData>>() {
-        });
+        return api.callWithAuth("GET", endpoint, null, new EventDataListTypeReference());
     }
 
     /**
@@ -143,8 +137,7 @@ public List<EventData> allData(Long eventId, @Nullable Long start, @Nullable Lon
      */
     public EventData getData(Long eventId, Long dataId) throws IOException {
         return api.callWithAuth("GET", "/events/" + eventId + "/data/get/" + dataId + '/', null,
-                new TypeReference<EventData>() {
-                });
+                new EventDataTypeReference());
     }
 
     /**
@@ -159,8 +152,7 @@ public EventData getData(Long eventId, Long dataId) throws IOException {
      */
     public EventData insertData(Long eventId, EventDataInsert data) throws IOException {
         return api.callWithAuth("POST", "/events/" + eventId + "/data/", data,
-                new TypeReference<EventData>() {
-                });
+                new EventDataTypeReference());
     }
 
     /**
@@ -175,8 +167,26 @@ public EventData insertData(Long eventId, EventDataInsert data) throws IOExcepti
      */
     public Msg deleteData(Long eventId, Long dataId) throws IOException {
         return api.callWithAuth("DELETE", "/events/" + eventId + "/data/" + dataId + '/', null,
-                new TypeReference<Msg>() {
-                });
+                new MsgTypeReference());
     }
 
+    /**
+     * Copied from the Intellij code analysis:
+     * A static inner class does not keep an implicit reference to its enclosing instance.
+     * This prevents a common cause of memory leaks and uses less memory per instance of the class.
+     */
+    private static class EventListTypeReference extends TypeReference<List<Event>> {
+    }
+
+    private static class EventTypeReference extends TypeReference<Event> {
+    }
+
+    private static class MsgTypeReference extends TypeReference<Msg> {
+    }
+
+    private static class EventDataListTypeReference extends TypeReference<List<EventData>> {
+    }
+
+    private static class EventDataTypeReference extends TypeReference<EventData> {
+    }
 }
diff --git a/src/main/java/com/coscale/sdk/client/metrics/MetricGroup.java b/src/main/java/com/coscale/sdk/client/metrics/MetricGroup.java
index bb5bffc..3224f98 100755
--- a/src/main/java/com/coscale/sdk/client/metrics/MetricGroup.java
+++ b/src/main/java/com/coscale/sdk/client/metrics/MetricGroup.java
@@ -4,6 +4,7 @@
 
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Objects;
+import com.google.common.collect.Lists;
 
 public class MetricGroup {
 
@@ -48,13 +49,13 @@ public MetricGroup(Long id, String source, java.util.List<Metric> metrics, Subje
             java.util.List<Long> metricIds, String type, Long version) {
         this.id = id;
         this.source = source;
-        this.metrics = metrics;
+        this.metrics = Lists.newArrayList(metrics); // Copy the contents, don't keep reference.
         this.subject = subject;
         this.description = description;
         this.name = name;
         this.state = state;
-        this.metricgroups = metricgroups;
-        this.metricIds = metricIds;
+        this.metricgroups = Lists.newArrayList(metricgroups);
+        this.metricIds = Lists.newArrayList(metricIds);
         this.type = type;
         this.version = version;
     }
diff --git a/src/main/java/com/coscale/sdk/client/metrics/MetricsApi.java b/src/main/java/com/coscale/sdk/client/metrics/MetricsApi.java
index 8bf6b88..de8045c 100755
--- a/src/main/java/com/coscale/sdk/client/metrics/MetricsApi.java
+++ b/src/main/java/com/coscale/sdk/client/metrics/MetricsApi.java
@@ -37,8 +37,7 @@ public MetricsApi(ApiClient api) {
      * @throws IOException
      */
     public List<Metric> all() throws IOException {
-        return api.callWithAuth("GET", "/metrics/", null, new TypeReference<List<Metric>>() {
-        });
+        return api.callWithAuth("GET", "/metrics/", null, new MetricListTypeReference());
     }
 
     /**
@@ -52,8 +51,7 @@ public List<Metric> all() throws IOException {
     public List<Metric> all(Options options) throws IOException {
         String url = "/metrics/";
         url += (options.hasQuery() ? "?" : "&") + options.query();
-        return api.callWithAuth("GET", url, null, new TypeReference<List<Metric>>() {
-        });
+        return api.callWithAuth("GET", url, null, new MetricListTypeReference());
     }
 
     /**
@@ -65,8 +63,7 @@ public List<Metric> all(Options options) throws IOException {
      * @throws IOException
      */
     public Metric get(long id) throws IOException {
-        return api.callWithAuth("GET", "/metrics/" + id + '/', null, new TypeReference<Metric>() {
-        });
+        return api.callWithAuth("GET", "/metrics/" + id + '/', null, new MetricTypeReference());
     }
 
     /**
@@ -78,8 +75,7 @@ public Metric get(long id) throws IOException {
      * @throws IOException
      */
     public Metric insert(MetricInsert metric) throws IOException {
-        return api.callWithAuth("POST", "/metrics/", metric, new TypeReference<Metric>() {
-        });
+        return api.callWithAuth("POST", "/metrics/", metric, new MetricTypeReference());
     }
 
     /**
@@ -91,8 +87,7 @@ public Metric insert(MetricInsert metric) throws IOException {
      * @throws IOException
      */
     public Msg delete(long id) throws IOException {
-        return api.callWithAuth("DELETE", "/metrics/" + id + '/', null, new TypeReference<Msg>() {
-        });
+        return api.callWithAuth("DELETE", "/metrics/" + id + '/', null, new MsgTypeReference());
     }
 
     /** Metric groups Calls */
@@ -105,8 +100,7 @@ public Msg delete(long id) throws IOException {
      */
     public List<MetricGroup> getAllMetricGroups() throws IOException {
         return api.callWithAuth("GET", "/metricgroups/", null,
-                new TypeReference<List<MetricGroup>>() {
-                });
+                new MetricGroupListTypeReference());
     }
 
     /**
@@ -121,8 +115,7 @@ public List<MetricGroup> getAllMetricGroups() throws IOException {
     public List<MetricGroup> getAllMetricGroups(Options options) throws IOException {
         String url = "/metricgroups/";
         url += (options.hasQuery() ? "?" : "&") + options.query();
-        return api.callWithAuth("GET", url, null, new TypeReference<List<MetricGroup>>() {
-        });
+        return api.callWithAuth("GET", url, null, new MetricGroupListTypeReference());
     }
 
     /**
@@ -135,8 +128,7 @@ public List<MetricGroup> getAllMetricGroups(Options options) throws IOException
      */
     public MetricGroup getMetricGroup(long id) throws IOException {
         return api.callWithAuth("GET", "/metricgroups/" + id + '/', null,
-                new TypeReference<MetricGroup>() {
-                });
+                new MetricGroupTypeReference());
     }
 
     /**
@@ -150,8 +142,7 @@ public MetricGroup getMetricGroup(long id) throws IOException {
      */
     public MetricGroup insertMetricGroup(MetricGroupInsert metricGroup) throws IOException {
         return api.callWithAuth("POST", "/metricgroups/", metricGroup,
-                new TypeReference<MetricGroup>() {
-                });
+                new MetricGroupTypeReference());
     }
 
     /**
@@ -164,8 +155,7 @@ public MetricGroup insertMetricGroup(MetricGroupInsert metricGroup) throws IOExc
      */
     public Msg deleteMetricGroup(long id) throws IOException {
         return api.callWithAuth("DELETE", "/metricgroups/" + id + '/', null,
-                new TypeReference<Msg>() {
-                });
+                new MsgTypeReference());
     }
 
     /**
@@ -178,8 +168,7 @@ public Msg deleteMetricGroup(long id) throws IOException {
      */
     public List<MetricGroup> addGroupToGroup(long childId, long parentId) throws IOException {
         return api.callWithAuth("POST", "/metricgroups/" + parentId + "/metricgroups/" + childId
-                + '/', null, new TypeReference<List<MetricGroup>>() {
-        });
+                + '/', null, new MetricGroupListTypeReference());
     }
 
     /**
@@ -192,8 +181,7 @@ public List<MetricGroup> addGroupToGroup(long childId, long parentId) throws IOE
      */
     public List<Metric> addMetricToGroup(long metricId, long groupId) throws IOException {
         return api.callWithAuth("POST", "/metricgroups/" + groupId + "/metrics/" + metricId + '/',
-                null, new TypeReference<List<Metric>>() {
-                });
+                null, new MetricListTypeReference());
     }
 
     /**
@@ -206,8 +194,7 @@ public List<Metric> addMetricToGroup(long metricId, long groupId) throws IOExcep
      */
     public List<Metric> getGroupMetrics(long groupId) throws IOException {
         return api.callWithAuth("GET", "/metricgroups/" + groupId + "/metrics/", null,
-                new TypeReference<List<Metric>>() {
-                });
+                new MetricListTypeReference());
     }
 
     /**
@@ -223,8 +210,7 @@ public List<Metric> getGroupMetrics(long groupId) throws IOException {
     public Msg deleteMetricFromGroup(long metricId, long groupId) throws IOException {
         return api.callWithAuth("DELETE",
                 "/metricgroups/" + groupId + "/metrics/" + metricId + '/', null,
-                new TypeReference<Msg>() {
-                });
+                new MsgTypeReference());
     }
 
     /**
@@ -237,8 +223,7 @@ public Msg deleteMetricFromGroup(long metricId, long groupId) throws IOException
      */
     public List<MetricGroup> getGroupsFromGroup(long groupId) throws IOException {
         return api.callWithAuth("GET", "/metricgroups/" + groupId + "/metricgroups/", null,
-                new TypeReference<List<MetricGroup>>() {
-                });
+                new MetricGroupListTypeReference());
     }
 
     /**
@@ -254,7 +239,26 @@ public List<MetricGroup> getGroupsFromGroup(long groupId) throws IOException {
      */
     public Msg deleteGroupFromGroup(long childId, long parentId) throws IOException {
         return api.callWithAuth("DELETE", "/metricgroups/" + parentId + "/metricgroups/" + childId
-                + '/', null, new TypeReference<Msg>() {
-        });
+                + '/', null, new MsgTypeReference());
+    }
+
+    /**
+     * Copied from the Intellij code analysis:
+     * A static inner class does not keep an implicit reference to its enclosing instance.
+     * This prevents a common cause of memory leaks and uses less memory per instance of the class.
+     */
+    private static class MetricListTypeReference extends TypeReference<List<Metric>> {
+    }
+
+    private static class MetricTypeReference extends TypeReference<Metric> {
+    }
+
+    private static class MsgTypeReference extends TypeReference<Msg> {
+    }
+
+    private static class MetricGroupListTypeReference extends TypeReference<List<MetricGroup>> {
+    }
+
+    private static class MetricGroupTypeReference extends TypeReference<MetricGroup> {
     }
 }
diff --git a/src/main/java/com/coscale/sdk/client/requests/Request.java b/src/main/java/com/coscale/sdk/client/requests/Request.java
index b408683..50da542 100644
--- a/src/main/java/com/coscale/sdk/client/requests/Request.java
+++ b/src/main/java/com/coscale/sdk/client/requests/Request.java
@@ -8,6 +8,7 @@
 import com.coscale.sdk.client.metrics.State;
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Objects;
+import com.google.common.collect.Lists;
 
 public class Request {
 
@@ -60,7 +61,7 @@ public Request(Protocol protocol, State state, String classifierConfig, Long ver
         this.id = id;
         this.parentId = parentId;
         this.classifierType = classifierType;
-        this.requests = requests;
+        this.requests = Lists.newArrayList(requests);
         this.source = source;
         this.description = description;
         this.priority = priority;
diff --git a/src/main/java/com/coscale/sdk/client/requests/RequestsApi.java b/src/main/java/com/coscale/sdk/client/requests/RequestsApi.java
index c6a48a1..026e0c4 100644
--- a/src/main/java/com/coscale/sdk/client/requests/RequestsApi.java
+++ b/src/main/java/com/coscale/sdk/client/requests/RequestsApi.java
@@ -37,8 +37,7 @@ public RequestsApi(ApiClient api) {
      * @throws IOException
      */
     public List<Request> all() throws IOException {
-        return api.callWithAuth("GET", "/requests/", null, new TypeReference<List<Request>>() {
-        });
+        return api.callWithAuth("GET", "/requests/", null, new RequestListTypeReference());
     }
 
     /**
@@ -52,8 +51,7 @@ public List<Request> all() throws IOException {
     public List<Request> all(Options options) throws IOException {
         String url = "/requests/";
         url += (options.hasQuery() ? "?" : "&") + options.query();
-        return api.callWithAuth("GET", url, null, new TypeReference<List<Request>>() {
-        });
+        return api.callWithAuth("GET", url, null, new RequestListTypeReference());
     }
 
     /**
@@ -65,8 +63,7 @@ public List<Request> all(Options options) throws IOException {
      * @throws IOException
      */
     public Request get(long id) throws IOException {
-        return api.callWithAuth("GET", "/requests/" + id + '/', null, new TypeReference<Request>() {
-        });
+        return api.callWithAuth("GET", "/requests/" + id + '/', null, new RequestTypeReference());
     }
 
     /**
@@ -82,7 +79,17 @@ public Request get(long id) throws IOException {
     public Request get(long id, Options options) throws IOException {
         String url = "/requests/" + id + '/';
         url += (options.hasQuery() ? "?" : "&") + options.query();
-        return api.callWithAuth("GET", url, null, new TypeReference<Request>() {
-        });
+        return api.callWithAuth("GET", url, null, new RequestTypeReference());
+    }
+
+    /**
+     * Copied from the Intellij code analysis:
+     * A static inner class does not keep an implicit reference to its enclosing instance.
+     * This prevents a common cause of memory leaks and uses less memory per instance of the class.
+     */
+    private static class RequestListTypeReference extends TypeReference<List<Request>> {
+    }
+
+    private static class RequestTypeReference extends TypeReference<Request> {
     }
 }
\ No newline at end of file
diff --git a/src/main/java/com/coscale/sdk/client/servers/Server.java b/src/main/java/com/coscale/sdk/client/servers/Server.java
index d658933..c84be72 100755
--- a/src/main/java/com/coscale/sdk/client/servers/Server.java
+++ b/src/main/java/com/coscale/sdk/client/servers/Server.java
@@ -8,6 +8,7 @@
 import com.coscale.sdk.client.metrics.State;
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Objects;
+import com.google.common.collect.Lists;
 
 public class Server {
 
@@ -49,14 +50,14 @@ public Server(Long id, String source, List<Metric> metrics, String description,
             List<ServerAttribute> attributes) {
         this.id = id;
         this.source = source;
-        this.metrics = metrics;
+        this.metrics = Lists.newArrayList(metrics);
         this.description = description;
         this.name = name;
         this.state = state;
-        this.children = children;
+        this.children = Lists.newArrayList(children);
         this.type = type;
         this.version = version;
-        this.attributes = attributes;
+        this.attributes = Lists.newArrayList(attributes);
     }
 
     public Server() {
diff --git a/src/main/java/com/coscale/sdk/client/servers/ServerGroup.java b/src/main/java/com/coscale/sdk/client/servers/ServerGroup.java
index aeb6df3..7a2cc32 100644
--- a/src/main/java/com/coscale/sdk/client/servers/ServerGroup.java
+++ b/src/main/java/com/coscale/sdk/client/servers/ServerGroup.java
@@ -7,6 +7,7 @@
 import com.coscale.sdk.client.metrics.State;
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Objects;
+import com.google.common.collect.Lists;
 
 public class ServerGroup {
 
@@ -44,11 +45,11 @@ public ServerGroup(Long id, String source, List<Server> servers, String descript
             String name, State state, List<ServerGroup> servergroups, String type, Long version) {
         this.id = id;
         this.source = source;
-        this.servers = servers;
+        this.servers = Lists.newArrayList(servers);
         this.description = description;
         this.name = name;
         this.state = state;
-        this.servergroups = servergroups;
+        this.servergroups = Lists.newArrayList(servergroups);
         this.type = type;
         this.version = version;
     }
diff --git a/src/main/java/com/coscale/sdk/client/servers/ServersApi.java b/src/main/java/com/coscale/sdk/client/servers/ServersApi.java
index 5f6d520..1df7baf 100755
--- a/src/main/java/com/coscale/sdk/client/servers/ServersApi.java
+++ b/src/main/java/com/coscale/sdk/client/servers/ServersApi.java
@@ -36,8 +36,7 @@ public ServersApi(ApiClient api) {
      * @throws IOException
      */
     public List<Server> all() throws IOException {
-        return api.callWithAuth("GET", "/servers/", null, new TypeReference<List<Server>>() {
-        });
+        return api.callWithAuth("GET", "/servers/", null, new ServerListTypeReference());
     }
 
     /**
@@ -51,8 +50,7 @@ public List<Server> all() throws IOException {
     public List<Server> all(Options options) throws IOException {
         String url = "/servers/";
         url += (options.hasQuery() ? "?" : "&") + options.query();
-        return api.callWithAuth("GET", url, null, new TypeReference<List<Server>>() {
-        });
+        return api.callWithAuth("GET", url, null, new ServerListTypeReference());
     }
 
     /**
@@ -65,8 +63,7 @@ public List<Server> all(Options options) throws IOException {
      */
     public Server getServer(long serverId) throws IOException {
         return api.callWithAuth("GET", "/servers/" + serverId + '/', null,
-                new TypeReference<Server>() {
-                });
+                new ServerTypeReference());
     }
 
     /**
@@ -82,8 +79,7 @@ public Server getServer(long serverId) throws IOException {
     public Server getServer(long serverId, Options options) throws IOException {
         String url = "/servers/" + serverId + '/';
         url += (options.hasQuery() ? "?" : "&") + options.query();
-        return api.callWithAuth("GET", url, null, new TypeReference<Server>() {
-        });
+        return api.callWithAuth("GET", url, null, new ServerTypeReference());
     }
 
     /**
@@ -96,8 +92,7 @@ public Server getServer(long serverId, Options options) throws IOException {
      * @throws IOException
      */
     public Server insert(ServerInsert serverInsert) throws IOException {
-        return api.callWithAuth("POST", "/servers/", serverInsert, new TypeReference<Server>() {
-        });
+        return api.callWithAuth("POST", "/servers/", serverInsert, new ServerTypeReference());
     }
 
     /**
@@ -110,8 +105,7 @@ public Server insert(ServerInsert serverInsert) throws IOException {
      */
     public Msg delete(long serverId) throws IOException {
         return api.callWithAuth("DELETE", "/servers/" + serverId + '/', null,
-                new TypeReference<Msg>() {
-                });
+                new MsgTypeReference());
     }
 
     /** Server groups Calls */
@@ -123,9 +117,7 @@ public Msg delete(long serverId) throws IOException {
      * @throws IOException
      */
     public List<ServerGroup> getAllServerGroups() throws IOException {
-        return api.callWithAuth("GET", "/servergroups/", null,
-                new TypeReference<List<ServerGroup>>() {
-                });
+        return api.callWithAuth("GET", "/servergroups/", null, new ServerGroupListTypeReference());
     }
 
     /**
@@ -140,8 +132,7 @@ public List<ServerGroup> getAllServerGroups() throws IOException {
     public List<ServerGroup> getAllServerGroups(Options options) throws IOException {
         String url = "/servergroups/";
         url += (options.hasQuery() ? "?" : "&") + options.query();
-        return api.callWithAuth("GET", url, null, new TypeReference<List<ServerGroup>>() {
-        });
+        return api.callWithAuth("GET", url, null, new ServerGroupListTypeReference());
     }
 
     /**
@@ -154,8 +145,7 @@ public List<ServerGroup> getAllServerGroups(Options options) throws IOException
      */
     public ServerGroup getServerGroup(long id) throws IOException {
         return api.callWithAuth("GET", "/servergroups/" + id + '/', null,
-                new TypeReference<ServerGroup>() {
-                });
+                new ServerGroupTypeReference());
     }
 
     /**
@@ -169,8 +159,7 @@ public ServerGroup getServerGroup(long id) throws IOException {
      */
     public ServerGroup insertServerGroup(ServerGroupInsert serverGroup) throws IOException {
         return api.callWithAuth("POST", "/servergroups/", serverGroup,
-                new TypeReference<ServerGroup>() {
-                });
+                new ServerGroupTypeReference());
     }
 
     /**
@@ -183,8 +172,7 @@ public ServerGroup insertServerGroup(ServerGroupInsert serverGroup) throws IOExc
      */
     public Msg deleteServerGroup(long id) throws IOException {
         return api.callWithAuth("DELETE", "/servergroups/" + id + '/', null,
-                new TypeReference<Msg>() {
-                });
+                new MsgTypeReference());
     }
 
     /**
@@ -197,8 +185,7 @@ public Msg deleteServerGroup(long id) throws IOException {
      */
     public List<ServerGroup> addGroupToGroup(long childId, long parentId) throws IOException {
         return api.callWithAuth("POST", "/servergroups/" + parentId + "/servergroups/" + childId
-                + '/', null, new TypeReference<List<ServerGroup>>() {
-        });
+                + '/', null, new ServerGroupListTypeReference());
     }
 
     /**
@@ -211,8 +198,7 @@ public List<ServerGroup> addGroupToGroup(long childId, long parentId) throws IOE
      */
     public List<Server> addServerToGroup(long serverId, long groupId) throws IOException {
         return api.callWithAuth("POST", "/servergroups/" + groupId + "/servers/" + serverId + '/',
-                null, new TypeReference<List<Server>>() {
-                });
+                null, new ServerListTypeReference());
     }
 
     /**
@@ -225,8 +211,7 @@ public List<Server> addServerToGroup(long serverId, long groupId) throws IOExcep
      */
     public List<Server> getGroupServers(long groupId) throws IOException {
         return api.callWithAuth("GET", "/servergroups/" + groupId + "/servers/", null,
-                new TypeReference<List<Server>>() {
-                });
+                new ServerListTypeReference());
     }
 
     /**
@@ -242,8 +227,7 @@ public List<Server> getGroupServers(long groupId) throws IOException {
     public Msg deleteServerFromGroup(long serverId, long groupId) throws IOException {
         return api.callWithAuth("DELETE",
                 "/servergroups/" + groupId + "/servers/" + serverId + '/', null,
-                new TypeReference<Msg>() {
-                });
+                new MsgTypeReference());
     }
 
     /**
@@ -256,8 +240,7 @@ public Msg deleteServerFromGroup(long serverId, long groupId) throws IOException
      */
     public List<ServerGroup> getGroupsFromGroup(long groupId) throws IOException {
         return api.callWithAuth("GET", "/servergroups/" + groupId + "/servergroups/", null,
-                new TypeReference<List<ServerGroup>>() {
-                });
+                new ServerGroupListTypeReference());
     }
 
     /**
@@ -273,7 +256,26 @@ public List<ServerGroup> getGroupsFromGroup(long groupId) throws IOException {
      */
     public Msg deleteGroupFromGroup(long childId, long parentId) throws IOException {
         return api.callWithAuth("DELETE", "/servergroups/" + parentId + "/servergroups/" + childId
-                + '/', null, new TypeReference<Msg>() {
-        });
+                + '/', null, new MsgTypeReference());
+    }
+
+    /**
+     * Copied from the Intellij code analysis:
+     * A static inner class does not keep an implicit reference to its enclosing instance.
+     * This prevents a common cause of memory leaks and uses less memory per instance of the class.
+     */
+    private static class ServerListTypeReference extends TypeReference<List<Server>> {
+    }
+
+    private static class ServerGroupListTypeReference extends TypeReference<List<ServerGroup>> {
+    }
+
+    private static class ServerTypeReference extends TypeReference<Server> {
+    }
+
+    private static class ServerGroupTypeReference extends TypeReference<ServerGroup> {
+    }
+
+    private static class MsgTypeReference extends TypeReference<Msg> {
     }
 }