Force id to be mandatory

Signed-off-by: Francisco Javier Tirado Sarti <ftirados@redhat.com>

Author: fjtirado

api/src/main/resources/schema/workflow.json

@@ -160,6 +160,7 @@
     }
   },
  "required": [
+        "id",
         "name",
         "version",
         "states"

validation/src/test/java/io/serverlessworkflow/validation/test/WorkflowValidationTest.java

@@ -58,7 +58,7 @@ public void testIncompleteYamlWithSchemaValidation() {
     List<ValidationError> validationErrors =
         workflowValidator.setSource("---\n" + "key: abc\n").validate();
     Assertions.assertNotNull(validationErrors);
-    Assertions.assertEquals(3, validationErrors.size());
+    Assertions.assertEquals(4, validationErrors.size());
   }
 
   @Test
@@ -119,11 +119,10 @@ public void testWorkflowMissingStatesIdAndKey() {
                     + "}")
             .validate();
     Assertions.assertNotNull(validationErrors);
-    Assertions.assertEquals(2, validationErrors.size());
+    Assertions.assertEquals(1, validationErrors.size());
 
     Assertions.assertEquals(
-        "Workflow id or key should not be empty", validationErrors.get(0).getMessage());
-    Assertions.assertEquals("No states found", validationErrors.get(1).getMessage());
+        "$.id: is missing but it is required", validationErrors.get(0).getMessage());
   }
 
   @Test