docs: public DocumentLoader addInjectedDoc(String url, String doc) throws JsonLdError {
          try {
              m_injectedDocs.put(url, JsonUtils.fromString(doc));
              return this;
          } catch (final Exception e) {
              throw new JsonLdError(JsonLdError.Error.LOADING_INJECTED_CONTEXT_FAILED, url, e);
          }
      }