feat(engine) - add BpmnErrorCodeProvider interface and implement custom error code handling

Author: sowmyahl21

engine/src/main/java/org/finos/fluxnova/bpm/engine/delegate/BpmnErrorCodeProvider.java

@@ -0,0 +1,13 @@
+package org.finos.fluxnova.bpm.engine.delegate;
+
+/**
+ * Interface to be implemented by exceptions that are intended to provide a BPMN error code.
+ * <p>
+ * Implement this interface in custom exception classes when you want to propagate a specific
+ * BPMN error code to the process engine. The {@link #getErrorCode()} method should return
+ * the BPMN error code associated with the exception.
+ */
+
+public interface BpmnErrorCodeProvider {
+    String getErrorCode();
+}

engine/src/main/java/org/finos/fluxnova/bpm/engine/impl/bpmn/helper/BpmnExceptionHandler.java

@@ -18,6 +18,7 @@
 
 import org.finos.fluxnova.bpm.engine.ProcessEngineException;
 import org.finos.fluxnova.bpm.engine.delegate.BpmnError;
+import org.finos.fluxnova.bpm.engine.delegate.BpmnErrorCodeProvider;
 import org.finos.fluxnova.bpm.engine.impl.ProcessEngineLogger;
 import org.finos.fluxnova.bpm.engine.impl.bpmn.behavior.BpmnBehaviorLogger;
 import org.finos.fluxnova.bpm.engine.impl.bpmn.parser.ErrorEventDefinition;
@@ -59,7 +60,11 @@ protected static void propagateExceptionAsError(Exception exception, ActivityExe
       throw exception;
     }
     else {
-      propagateError(null, exception.getMessage(),exception, execution);
+      String errorCode = null;
+      if (exception instanceof BpmnErrorCodeProvider) {
+        errorCode = ((BpmnErrorCodeProvider) exception).getErrorCode();
+      }
+      propagateError(errorCode, exception.getMessage(),exception, execution);
     }
   }
 

engine/src/test/java/org/finos/fluxnova/bpm/engine/test/bpmn/behavior/BpmnErrorCodeProviderTest.java

@@ -0,0 +1,20 @@
+package org.finos.fluxnova.bpm.engine.test.bpmn.behavior;
+
+import org.finos.fluxnova.bpm.engine.delegate.BpmnErrorCodeProvider;
+import org.junit.Test;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class BpmnErrorCodeProviderTest {
+    static class CustomBpmnException extends Exception implements BpmnErrorCodeProvider {
+        @Override
+        public String getErrorCode() {
+            return "CUSTOM_ERROR_CODE";
+        }
+    }
+
+    @Test
+    public void shouldReturnCustomErrorCode() {
+        CustomBpmnException exception = new CustomBpmnException();
+        assertThat(exception.getErrorCode()).isEqualTo("CUSTOM_ERROR_CODE");
+    }
+}