code: private void lockContext(String contextId) throws EKBConcurrentException {
          if (mode == ContextLockingMode.DEACTIVATED) {
              return;
          }
          synchronized (activeWritingContexts) {
              if (activeWritingContexts.contains(contextId)) {
                  throw new EKBConcurrentException("There is already a writing process active in the context.");
              }
  
              activeWritingContexts.add(contextId);
          }
      }
docs: If the context locking mode is activated, this method locks the given context for writing operations. If this
  context is already locked, an EKBConcurrentException is thrown.