Updated implementation for IWorkflowSystemMetadataRepository to return empty list instead of nulll

provider/workflow-aws/src/main/java/org/opengroup/osdu/workflow/aws/repository/AwsWorkflowSystemMetadataRepository.java

@@ -5,6 +5,7 @@ import org.opengroup.osdu.workflow.provider.interfaces.IWorkflowSystemMetadataRe
 import org.springframework.stereotype.Repository;
 import org.springframework.web.context.annotation.RequestScope;
 
+import java.util.ArrayList;
 import java.util.List;
 
 @Repository
@@ -47,6 +48,6 @@ public class AwsWorkflowSystemMetadataRepository implements IWorkflowSystemMetad
    */
   @Override
   public List<WorkflowMetadata> getAllSystemWorkflow(String prefix) {
-    return null;
+    return new ArrayList<>();
   }
 }

provider/workflow-gcp/src/main/java/org/opengroup/osdu/workflow/provider/gcp/repository/GcpWorkflowSystemMetadataRepository.java

@@ -6,6 +6,7 @@ import org.opengroup.osdu.workflow.model.WorkflowMetadata;
 import org.opengroup.osdu.workflow.provider.interfaces.IWorkflowSystemMetadataRepository;
 import org.springframework.stereotype.Service;
 
+import java.util.ArrayList;
 import java.util.List;
 
 @Service
@@ -49,6 +50,6 @@ public class GcpWorkflowSystemMetadataRepository implements IWorkflowSystemMetad
    */
   @Override
   public List<WorkflowMetadata> getAllSystemWorkflow(String prefix) {
-    return null;
+    return new ArrayList<>();
   }
 }

provider/workflow-ibm/src/main/java/org/opengroup/osdu/workflow/provider/ibm/repository/WorkflowSystemMetadataRepository.java

@@ -5,6 +5,7 @@ import org.opengroup.osdu.workflow.model.WorkflowMetadata;
 import org.opengroup.osdu.workflow.provider.interfaces.IWorkflowSystemMetadataRepository;
 import org.springframework.stereotype.Component;
 
+import java.util.ArrayList;
 import java.util.List;
 
 @Component
@@ -47,6 +48,6 @@ public class WorkflowSystemMetadataRepository implements IWorkflowSystemMetadata
    */
   @Override
   public List<WorkflowMetadata> getAllSystemWorkflow(String prefix) {
-    return null;
+    return new ArrayList<>();
   }
 }