Fixed NullpointerException

core/src/main/java/com/netflix/conductor/core/metadata/MetadataMapperService.java

@@ -91,7 +91,7 @@ Optional<WorkflowDef> lookupLatestWorkflowDefinition(String workflowName) {
     }
 
     public Workflow populateWorkflowWithDefinitions(Workflow workflow) {
-
+        Preconditions.checkNotNull(workflow, "workflow cannot be null");
         WorkflowDef workflowDefinition = Optional.ofNullable(workflow.getWorkflowDefinition())
                 .orElseGet(() -> {
                     WorkflowDef wd = lookupForWorkflowDefinition(workflow.getWorkflowName(), workflow.getWorkflowVersion());
@@ -115,6 +115,7 @@ public Workflow populateWorkflowWithDefinitions(Workflow workflow) {
     }
 
     public WorkflowDef populateTaskDefinitions(WorkflowDef workflowDefinition) {
+        Preconditions.checkNotNull(workflowDefinition, "workflowDefinition cannot be null");
         workflowDefinition.collectTasks().forEach(
                 this::populateWorkflowTaskWithDefinition
         );
@@ -123,6 +124,7 @@ public WorkflowDef populateTaskDefinitions(WorkflowDef workflowDefinition) {
     }
 
     private WorkflowTask populateWorkflowTaskWithDefinition(WorkflowTask workflowTask) {
+        Preconditions.checkNotNull(workflowTask, "WorkflowTask cannot be null");
         if (shouldPopulateDefinition(workflowTask)) {
             workflowTask.setTaskDefinition(metadataDAO.getTaskDef(workflowTask.getName()));
         } else if (workflowTask.getType().equals(TaskType.SUB_WORKFLOW.name())) {
@@ -132,6 +134,7 @@ private WorkflowTask populateWorkflowTaskWithDefinition(WorkflowTask workflowTas
     }
 
     private void populateVersionForSubWorkflow(WorkflowTask workflowTask) {
+        Preconditions.checkNotNull(workflowTask, "WorkflowTask cannot be null");
         SubWorkflowParams subworkflowParams = workflowTask.getSubWorkflowParam();
         if (subworkflowParams.getVersion() == null) {
             String subWorkflowName = subworkflowParams.getName();
@@ -150,6 +153,7 @@ private void populateVersionForSubWorkflow(WorkflowTask workflowTask) {
     }
 
     private void checkNotEmptyDefinitions(WorkflowDef workflowDefinition) {
+        Preconditions.checkNotNull(workflowDefinition, "WorkflowDefinition cannot be null");
 
         // Obtain the names of the tasks with missing definitions
         Set<String> missingTaskDefinitionNames = workflowDefinition.collectTasks().stream()
@@ -165,11 +169,14 @@ private void checkNotEmptyDefinitions(WorkflowDef workflowDefinition) {
     }
 
     public Task populateTaskWithDefinition(Task task) {
+        Preconditions.checkNotNull(task, "Task cannot be null");
         populateWorkflowTaskWithDefinition(task.getWorkflowTask());
         return task;
     }
 
     public static boolean shouldPopulateDefinition(WorkflowTask workflowTask) {
+        Preconditions.checkNotNull(workflowTask, "WorkflowTask cannot be null");
+        Preconditions.checkNotNull(workflowTask.getType(), "WorkflowTask type cannot be null");
         return workflowTask.getType().equals(TaskType.SIMPLE.name()) &&
                 workflowTask.getTaskDefinition() == null;
     }