code: private com.buschmais.xo.spi.reflection.AnnotatedElement<?> getRelationDefinitionElement(PropertyMethod propertyMethod) {
          if (propertyMethod.getByMetaAnnotationOfProperty(RelationDefinition.class) != null) {
              return propertyMethod;
          }
          Annotation[] declaredAnnotations = propertyMethod.getAnnotationsOfProperty();
          for (int i = 0; i < declaredAnnotations.length; i++) {
              com.buschmais.xo.spi.reflection.AnnotatedElement<?> annotationTypeElement = new AnnotatedType(declaredAnnotations[i].annotationType());
              if (annotationTypeElement.getByMetaAnnotation(RelationDefinition.class) != null) {
                  return annotationTypeElement;
              }
          }
          return propertyMethod;
      }
docs: Determines the {@link AnnotatedElement} which is annotated with
  {@link RelationDefinition}.
  
  @param propertyMethod
  The property method to start with.
  @return The annotated element.