Changes after comments

Author: fjtirado

api/src/main/java/io/serverlessworkflow/api/serializers/WorkflowSerializer.java

@@ -160,10 +160,11 @@ public void serialize(Workflow workflow, JsonGenerator gen, SerializerProvider p
     }
 
     if (workflow.getConstants() != null) {
-      if (!workflow.getConstants().getConstantsDef().isEmpty()) {  
-          gen.writeObjectField("constants", workflow.getConstants().getConstantsDef());
+      if (workflow.getConstants().getConstantsDef() != null
+          && !workflow.getConstants().getConstantsDef().isEmpty()) {
+        gen.writeObjectField("constants", workflow.getConstants().getConstantsDef());
       } else if (workflow.getConstants().getRefValue() != null) {
-          gen.writeStringField("constants", workflow.getConstants().getRefValue());
+        gen.writeStringField("constants", workflow.getConstants().getRefValue());
       }
     }
 

api/src/test/java/io/serverlessworkflow/api/test/MarkupToWorkflowTest.java

@@ -569,8 +569,7 @@ public void testConstants(String workflowLocation) {
     JsonNode serbianTranslationNode = translationDogNode.get("Serbian");
     assertEquals("pas", serbianTranslationNode.asText());
   }
-  
-  
+
   @ParameterizedTest
   @ValueSource(strings = {"/features/constantsRef.json", "/features/constantsRef.yml"})
   public void testConstantsRef(String workflowLocation) {
@@ -583,9 +582,8 @@ public void testConstantsRef(String workflowLocation) {
 
     assertNotNull(workflow.getConstants());
     Constants constants = workflow.getConstants();
-    assertNotNull(constants.getRefValue());
+    assertEquals("constantValues.json", constants.getRefValue());
   }
-  
 
   @ParameterizedTest
   @ValueSource(strings = {"/features/timeouts.json", "/features/timeouts.yml"})

api/src/test/java/io/serverlessworkflow/api/test/WorkflowToMarkupTest.java

@@ -32,6 +32,7 @@
 import io.serverlessworkflow.api.start.Start;
 import io.serverlessworkflow.api.states.SleepState;
 import io.serverlessworkflow.api.workflow.Auth;
+import io.serverlessworkflow.api.workflow.Constants;
 import io.serverlessworkflow.api.workflow.Events;
 import io.serverlessworkflow.api.workflow.Functions;
 import java.util.Arrays;
@@ -47,6 +48,7 @@ public void testSingleState() {
             .withName("test-workflow-name")
             .withVersion("1.0")
             .withStart(new Start().withSchedule(new Schedule().withInterval("PT1S")))
+            .withConstants(new Constants("constantsValues.json"))
             .withStates(
                 Arrays.asList(
                     new SleepState()
@@ -62,11 +64,13 @@ public void testSingleState() {
 
     assertNotNull(workflow);
     assertNotNull(workflow.getStart());
+    Constants constants = workflow.getConstants();
+    assertNotNull(constants);
+    assertEquals("constantsValues.json", constants.getRefValue());
     assertEquals(1, workflow.getStates().size());
     State state = workflow.getStates().get(0);
     assertTrue(state instanceof SleepState);
     assertNotNull(state.getEnd());
-
     assertNotNull(Workflow.toJson(workflow));
     assertNotNull(Workflow.toYaml(workflow));
   }

api/src/test/resources/features/constantsRef.json

@@ -5,7 +5,7 @@
   "name": "Custom secrets flow",
   "expressionLang": "abc",
   "start": "TestFunctionRefs",
-  "constants": "contantsValues.json",
+  "constants": "constantValues.json",
   "states": [
     {
       "name": "TestFunctionRefs",