code: public Map<String, AnnotationDefinition> getDefinitionMap() {
          if (definitions == null) {
              return emptyMap();
          }
          final Map<String, AnnotationDefinition> ret =
                  new HashMap<String, AnnotationDefinition>(definitions.size());
          for (final AnnotationDefinition ad : definitions) {
              ret.put(ad.getId(), ad);
          }
          return ret;
      }
docs: Returns the document's annotation definitions as a mapped keyed by
  annotation definition {@link AnnotationDefinition#getId() identifier}.
  
  @return Non-null map of annotation definition identifiers to instances,
  which may be empty