code: public OperationBuilder addInputStream(final InputStream in) {
          Assert.checkNotNullParam("in", in);
          if (inputStreams == null) {
              inputStreams = new ArrayList<InputStream>();
          }
          inputStreams.add(in);
          return this;
      }
docs: Associate an input stream with the operation. Closing the input stream
  is the responsibility of the caller.
  
  @param in  the input stream. Cannot be {@code null}
  @return a builder than can be used to continue building the operation