Addressed static code analysis warnings

pom.xml

@@ -100,6 +100,12 @@
             <groupId>org.apache.logging.log4j</groupId>
             <artifactId>log4j-core</artifactId>
         </dependency>
+        <!-- scope: provided -->
+        <dependency>
+            <groupId>com.github.spotbugs</groupId>
+            <artifactId>spotbugs-annotations</artifactId>
+            <scope>provided</scope>
+        </dependency>
         <!-- scope: test -->
         <dependency>
             <groupId>org.glassfish.jaxb</groupId>
@@ -174,6 +180,7 @@
                     <target>${maven.compiler.target}</target>
                     <compilerArgs>
                         <compilerArg>-proc:full</compilerArg>
+                        <compilerArg>-Xlint:deprecation</compilerArg>
                     </compilerArgs>
                 </configuration>
             </plugin>
@@ -266,10 +273,21 @@
             <plugin>
                 <groupId>com.github.spotbugs</groupId>
                 <artifactId>spotbugs-maven-plugin</artifactId>
+                <configuration>
+                    <excludeFilterFile>spotbugs-exclude.xml</excludeFilterFile>
+                </configuration>
             </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-pmd-plugin</artifactId>
+                <configuration>
+                    <minimumTokens>150</minimumTokens>
+                    <excludes>
+                        <!-- Exclude shift modifications from CPD as duplication between Integer/Long is acceptable -->
+                        <exclude>**/integer/*ShiftModification.java</exclude>
+                        <exclude>**/longint/*ShiftModification.java</exclude>
+                    </excludes>
+                </configuration>
             </plugin>
         </plugins>
     </build>

spotbugs-exclude.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<FindBugsFilter>
+    <!-- Ignore EI_EXPOSE_REP and EI_EXPOSE_REP2 warnings -->
+    <!-- These are intentionally ignored because this library is designed for runtime 
+         modification of variables, and defensive copying would impact performance 
+         without significant security benefits for this use case -->
+    <Match>
+        <Bug pattern="EI_EXPOSE_REP"/>
+    </Match>
+    <Match>
+        <Bug pattern="EI_EXPOSE_REP2"/>
+    </Match>
+</FindBugsFilter>

src/main/java/de/rub/nds/modifiablevariable/ModifiableVariableHolder.java

@@ -7,7 +7,7 @@
  */
 package de.rub.nds.modifiablevariable;
 
-import de.rub.nds.modifiablevariable.util.ArrayConverter;
+import de.rub.nds.modifiablevariable.util.DataConverter;
 import de.rub.nds.modifiablevariable.util.ReflectionHelper;
 import jakarta.xml.bind.annotation.XmlType;
 import java.io.Serializable;
@@ -194,7 +194,7 @@ protected String getExtendedString(int depth) {
                     stringBuilder.append("\t".repeat(Math.max(0, depth)));
                     stringBuilder.append(field.getName());
                     stringBuilder.append(": ");
-                    stringBuilder.append(ArrayConverter.bytesToHexString(temp));
+                    stringBuilder.append(DataConverter.bytesToHexString(temp));
                     stringBuilder.append("\n");
                 }
                 if (tempObject instanceof ModifiableVariableHolder) {

src/main/java/de/rub/nds/modifiablevariable/VariableModification.java

@@ -10,7 +10,7 @@
 import static de.rub.nds.modifiablevariable.util.StringUtil.backslashEscapeString;
 
 import com.fasterxml.jackson.annotation.JsonTypeInfo;
-import de.rub.nds.modifiablevariable.util.ArrayConverter;
+import de.rub.nds.modifiablevariable.util.DataConverter;
 import jakarta.xml.bind.annotation.XmlAccessType;
 import jakarta.xml.bind.annotation.XmlAccessorType;
 import jakarta.xml.bind.annotation.XmlTransient;
@@ -137,7 +137,7 @@ protected void debug(E value) {
             } else {
                 String valueString =
                         switch (value) {
-                            case byte[] bytes -> ArrayConverter.bytesToHexString(bytes);
+                            case byte[] bytes -> DataConverter.bytesToHexString(bytes);
                             case String s -> backslashEscapeString(s);
                             default -> value.toString();
                         };

src/main/java/de/rub/nds/modifiablevariable/biginteger/ModifiableBigInteger.java

@@ -8,7 +8,7 @@
 package de.rub.nds.modifiablevariable.biginteger;
 
 import de.rub.nds.modifiablevariable.ModifiableVariable;
-import de.rub.nds.modifiablevariable.util.ArrayConverter;
+import de.rub.nds.modifiablevariable.util.DataConverter;
 import jakarta.xml.bind.annotation.XmlRootElement;
 import java.math.BigInteger;
 
@@ -108,7 +108,7 @@ public boolean isOriginalValueModified() {
      * @return The byte array representation of the BigInteger
      */
     public byte[] getByteArray() {
-        return ArrayConverter.bigIntegerToByteArray(getValue());
+        return DataConverter.bigIntegerToByteArray(getValue());
     }
 
     /**
@@ -118,7 +118,7 @@ public byte[] getByteArray() {
      * @return The byte array representation of the BigInteger
      */
     public byte[] getByteArray(int size) {
-        return ArrayConverter.bigIntegerToByteArray(getValue(), size, true);
+        return DataConverter.bigIntegerToByteArray(getValue(), size, true);
     }
 
     /**

src/main/java/de/rub/nds/modifiablevariable/bool/BooleanExplicitValueModification.java

@@ -8,6 +8,7 @@
 package de.rub.nds.modifiablevariable.bool;
 
 import de.rub.nds.modifiablevariable.VariableModification;
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 import jakarta.xml.bind.annotation.XmlRootElement;
 
 /**
@@ -76,6 +77,10 @@ public BooleanExplicitValueModification createCopy() {
      * @return The explicit value, or null if input was null
      */
     @Override
+    @SuppressFBWarnings(
+            value = "NP_BOOLEAN_RETURN_NULL",
+            justification =
+                    "Returning null for null input is intentional design for null-safety in modification chain")
     protected Boolean modifyImplementationHook(Boolean input) {
         if (input == null) {
             return null;

src/main/java/de/rub/nds/modifiablevariable/bool/BooleanToggleModification.java

@@ -8,6 +8,7 @@
 package de.rub.nds.modifiablevariable.bool;
 
 import de.rub.nds.modifiablevariable.VariableModification;
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 import jakarta.xml.bind.annotation.XmlRootElement;
 
 /**
@@ -27,23 +28,14 @@ public BooleanToggleModification() {
         super();
     }
 
-    /**
-     * Copy constructor.
-     *
-     * @param other The modification to copy
-     */
-    public BooleanToggleModification(BooleanToggleModification other) {
-        super();
-    }
-
     /**
      * Creates a deep copy of this modification.
      *
      * @return A new instance of BooleanToggleModification
      */
     @Override
     public BooleanToggleModification createCopy() {
-        return new BooleanToggleModification(this);
+        return new BooleanToggleModification();
     }
 
     /**
@@ -59,6 +51,10 @@ public BooleanToggleModification createCopy() {
      * @return The inverted Boolean value, or null if the input is null
      */
     @Override
+    @SuppressFBWarnings(
+            value = "NP_BOOLEAN_RETURN_NULL",
+            justification =
+                    "Returning null for null input is intentional design for null-safety in modification chain")
     protected Boolean modifyImplementationHook(Boolean input) {
         if (input == null) {
             return null;

src/main/java/de/rub/nds/modifiablevariable/bytearray/ByteArrayAppendValueModification.java

@@ -8,7 +8,7 @@
 package de.rub.nds.modifiablevariable.bytearray;
 
 import de.rub.nds.modifiablevariable.VariableModification;
-import de.rub.nds.modifiablevariable.util.ArrayConverter;
+import de.rub.nds.modifiablevariable.util.DataConverter;
 import de.rub.nds.modifiablevariable.util.UnformattedByteArrayAdapter;
 import jakarta.xml.bind.annotation.XmlRootElement;
 import jakarta.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
@@ -96,7 +96,7 @@ protected byte[] modifyImplementationHook(byte[] input) {
         if (input == null) {
             return null;
         }
-        return ArrayConverter.concatenate(input, bytesToAppend);
+        return DataConverter.concatenate(input, bytesToAppend);
     }
 
     /**
@@ -167,7 +167,7 @@ public boolean equals(Object obj) {
     @Override
     public String toString() {
         return "ByteArrayAppendValueModification{bytesToAppend="
-                + ArrayConverter.bytesToHexString(bytesToAppend)
+                + DataConverter.bytesToHexString(bytesToAppend)
                 + "}";
     }
 }

src/main/java/de/rub/nds/modifiablevariable/bytearray/ByteArrayDeleteModification.java

@@ -8,7 +8,7 @@
 package de.rub.nds.modifiablevariable.bytearray;
 
 import de.rub.nds.modifiablevariable.VariableModification;
-import de.rub.nds.modifiablevariable.util.ArrayConverter;
+import de.rub.nds.modifiablevariable.util.DataConverter;
 import jakarta.xml.bind.annotation.XmlRootElement;
 import java.util.Arrays;
 
@@ -114,7 +114,7 @@ protected byte[] modifyImplementationHook(byte[] input) {
         byte[] ret1 = Arrays.copyOf(input, deleteStartPosition);
         if (deleteEndPosition < input.length) {
             byte[] ret2 = Arrays.copyOfRange(input, deleteEndPosition, input.length);
-            return ArrayConverter.concatenate(ret1, ret2);
+            return DataConverter.concatenate(ret1, ret2);
         }
         return ret1;
     }

src/main/java/de/rub/nds/modifiablevariable/bytearray/ByteArrayDuplicateModification.java

@@ -8,7 +8,7 @@
 package de.rub.nds.modifiablevariable.bytearray;
 
 import de.rub.nds.modifiablevariable.VariableModification;
-import de.rub.nds.modifiablevariable.util.ArrayConverter;
+import de.rub.nds.modifiablevariable.util.DataConverter;
 import jakarta.xml.bind.annotation.XmlRootElement;
 
 /**
@@ -31,15 +31,6 @@ public ByteArrayDuplicateModification() {
         super();
     }
 
-    /**
-     * Copy constructor for creating a deep copy of an existing modification.
-     *
-     * @param other The modification to copy
-     */
-    public ByteArrayDuplicateModification(ByteArrayDuplicateModification other) {
-        super();
-    }
-
     /**
      * Creates a deep copy of this modification.
      *
@@ -49,7 +40,7 @@ public ByteArrayDuplicateModification(ByteArrayDuplicateModification other) {
      */
     @Override
     public ByteArrayDuplicateModification createCopy() {
-        return new ByteArrayDuplicateModification(this);
+        return new ByteArrayDuplicateModification();
     }
 
     /**
@@ -72,7 +63,7 @@ protected byte[] modifyImplementationHook(byte[] input) {
         if (input == null) {
             return null;
         }
-        return ArrayConverter.concatenate(input, input);
+        return DataConverter.concatenate(input, input);
     }
 
     /**

src/main/java/de/rub/nds/modifiablevariable/bytearray/ByteArrayExplicitValueModification.java

@@ -8,7 +8,7 @@
 package de.rub.nds.modifiablevariable.bytearray;
 
 import de.rub.nds.modifiablevariable.VariableModification;
-import de.rub.nds.modifiablevariable.util.ArrayConverter;
+import de.rub.nds.modifiablevariable.util.DataConverter;
 import de.rub.nds.modifiablevariable.util.UnformattedByteArrayAdapter;
 import jakarta.xml.bind.annotation.XmlRootElement;
 import jakarta.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
@@ -148,7 +148,7 @@ public boolean equals(Object obj) {
     public String toString() {
         return "ByteArrayExplicitValueModification{"
                 + "explicitValue="
-                + ArrayConverter.bytesToHexString(explicitValue)
+                + DataConverter.bytesToHexString(explicitValue)
                 + '}';
     }
 }

src/main/java/de/rub/nds/modifiablevariable/bytearray/ByteArrayInsertValueModification.java

@@ -8,7 +8,7 @@
 package de.rub.nds.modifiablevariable.bytearray;
 
 import de.rub.nds.modifiablevariable.VariableModification;
-import de.rub.nds.modifiablevariable.util.ArrayConverter;
+import de.rub.nds.modifiablevariable.util.DataConverter;
 import de.rub.nds.modifiablevariable.util.UnformattedByteArrayAdapter;
 import jakarta.xml.bind.annotation.XmlRootElement;
 import jakarta.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
@@ -118,9 +118,9 @@ protected byte[] modifyImplementationHook(byte[] input) {
         byte[] ret1 = Arrays.copyOf(input, insertPosition);
         if (insertPosition < input.length) {
             byte[] ret2 = Arrays.copyOfRange(input, insertPosition, input.length);
-            return ArrayConverter.concatenate(ret1, bytesToInsert, ret2);
+            return DataConverter.concatenate(ret1, bytesToInsert, ret2);
         }
-        return ArrayConverter.concatenate(ret1, bytesToInsert);
+        return DataConverter.concatenate(ret1, bytesToInsert);
     }
 
     /**
@@ -215,7 +215,7 @@ public boolean equals(Object obj) {
     public String toString() {
         return "ByteArrayInsertModification{"
                 + "bytesToInsert="
-                + ArrayConverter.bytesToHexString(bytesToInsert)
+                + DataConverter.bytesToHexString(bytesToInsert)
                 + ", startPosition="
                 + startPosition
                 + '}';

src/main/java/de/rub/nds/modifiablevariable/bytearray/ByteArrayPrependValueModification.java

@@ -8,7 +8,7 @@
 package de.rub.nds.modifiablevariable.bytearray;
 
 import de.rub.nds.modifiablevariable.VariableModification;
-import de.rub.nds.modifiablevariable.util.ArrayConverter;
+import de.rub.nds.modifiablevariable.util.DataConverter;
 import de.rub.nds.modifiablevariable.util.UnformattedByteArrayAdapter;
 import jakarta.xml.bind.annotation.XmlRootElement;
 import jakarta.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
@@ -98,7 +98,7 @@ protected byte[] modifyImplementationHook(byte[] input) {
         if (input == null) {
             return null;
         }
-        return ArrayConverter.concatenate(bytesToPrepend, input);
+        return DataConverter.concatenate(bytesToPrepend, input);
     }
 
     /**
@@ -169,7 +169,7 @@ public boolean equals(Object obj) {
     @Override
     public String toString() {
         return "ByteArrayPrependValueModification{bytesToPrepend="
-                + ArrayConverter.bytesToHexString(bytesToPrepend)
+                + DataConverter.bytesToHexString(bytesToPrepend)
                 + "}";
     }
 }

src/main/java/de/rub/nds/modifiablevariable/bytearray/ByteArrayXorModification.java

@@ -8,7 +8,7 @@
 package de.rub.nds.modifiablevariable.bytearray;
 
 import de.rub.nds.modifiablevariable.VariableModification;
-import de.rub.nds.modifiablevariable.util.ArrayConverter;
+import de.rub.nds.modifiablevariable.util.DataConverter;
 import de.rub.nds.modifiablevariable.util.UnformattedByteArrayAdapter;
 import jakarta.xml.bind.annotation.XmlRootElement;
 import jakarta.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
@@ -126,10 +126,10 @@ protected byte[] modifyImplementationHook(byte[] input) {
     /**
      * Gets the byte array used for the XOR operation.
      *
-     * @return The XOR byte array
+     * @return A copy of the XOR byte array
      */
     public byte[] getXor() {
-        return xor;
+        return xor == null ? null : xor.clone();
     }
 
     /**
@@ -138,7 +138,7 @@ public byte[] getXor() {
      * @param xor The new XOR byte array
      */
     public void setXor(byte[] xor) {
-        this.xor = xor;
+        this.xor = xor == null ? null : xor.clone();
     }
 
     /**
@@ -208,7 +208,7 @@ public boolean equals(Object obj) {
     public String toString() {
         return "ByteArrayXorModification{"
                 + "xor="
-                + ArrayConverter.bytesToHexString(xor)
+                + DataConverter.bytesToHexString(xor)
                 + ", startPosition="
                 + startPosition
                 + '}';