feat(calendar): add EventCreated trigger for Google Calendar monitoring

src/main/java/io/kestra/plugin/googleworkspace/calendar/AbstractCalendarTrigger.java

@@ -0,0 +1,56 @@
+package io.kestra.plugin.googleworkspace.calendar;
+
+import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
+import com.google.api.client.json.gson.GsonFactory;
+import com.google.api.services.calendar.Calendar;
+import com.google.auth.http.HttpCredentialsAdapter;
+import com.google.auth.oauth2.GoogleCredentials;
+import io.kestra.core.models.property.Property;
+import io.kestra.core.models.triggers.AbstractTrigger;
+import io.kestra.core.runners.RunContext;
+import io.kestra.plugin.googleworkspace.GcpInterface;
+import io.swagger.v3.oas.annotations.media.Schema;
+import jakarta.validation.constraints.NotNull;
+import lombok.EqualsAndHashCode;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.ToString;
+import lombok.experimental.SuperBuilder;
+
+import java.io.ByteArrayInputStream;
+import java.nio.charset.StandardCharsets;
+
+@SuperBuilder
+@ToString
+@EqualsAndHashCode
+@Getter
+@NoArgsConstructor
+public abstract class AbstractCalendarTrigger extends AbstractTrigger implements GcpInterface {
+    private static final String APPLICATION_NAME = "Kestra";
+
+    @Schema(
+        title = "The Google Cloud service account key",
+        description = "Service account JSON key with access to Google Calendar API. " +
+            "The service account must have read access to the calendars you want to monitor. " +
+            "Share calendars with the service account's email address (found in the JSON key)."
+    )
+    @NotNull
+    protected Property<String> serviceAccount;
+
+    protected Calendar connection(RunContext runContext) throws Exception {
+        String renderedServiceAccount = runContext.render(this.serviceAccount).as(String.class).orElseThrow();
+        var renderedScopes = runContext.render(this.getScopes()).asList(String.class);
+
+        GoogleCredentials credentials = GoogleCredentials
+            .fromStream(new ByteArrayInputStream(renderedServiceAccount.getBytes(StandardCharsets.UTF_8)))
+            .createScoped(renderedScopes);
+
+        return new Calendar.Builder(
+            GoogleNetHttpTransport.newTrustedTransport(),
+            GsonFactory.getDefaultInstance(),
+            new HttpCredentialsAdapter(credentials)
+        )
+            .setApplicationName(APPLICATION_NAME)
+            .build();
+    }
+}