code: public <T> AsyncMutateInBuilder replace(String path, T fragment) {
          if (StringUtil.isNullOrEmpty(path)) {
              throw new IllegalArgumentException("Path must not be empty for replace");
          }
          this.mutationSpecs.add(new MutationSpec(Mutation.REPLACE, path, fragment));
          return this;
      }
docs: Replace an existing value by the given fragment.
  
  @param path the path where the value to replace is.
  @param fragment the new value.