Return true in case body is null just like existing EnsureNonNull han…

…dler

nullaway/src/main/java/com/uber/nullaway/handlers/contract/fieldcontract/EnsuresNonNullIfHandler.java

@@ -85,7 +85,7 @@ public EnsuresNonNullIfHandler() {
   protected boolean validateAnnotationSemantics(
       MethodTree tree, MethodAnalysisContext methodAnalysisContext) {
     if (tree.getBody() == null) {
-      return false;
+      return true;
     }
 
     // clean up state variables, as we are visiting a new annotated method