code: private WsByteBuffer getSoleWriteContextBuffer() {
        if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.entry(this, tc, "getSoleWriteContextBuffer");
        WsByteBuffer writeBuffer = null;
        final WsByteBuffer[] writeBuffers = writeCtx.getBuffers();
        if (writeBuffers != null) {
           final int writeBuffersSize = writeBuffers.length;
           if (writeBuffersSize > 0) {
              writeBuffer = writeBuffers[0];
              if (writeBuffersSize > 1) {
                 writeCtx.setBuffer(writeBuffer);
                 for (int i = 1; i < writeBuffersSize; i++) {
                    if (writeBuffers[i] != null) writeBuffers[i].release();
                 }
              }
           }
        }
        if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.exit(this, tc, "getSoleWriteContextBuffer", writeBuffer);
        return writeBuffer;
     }
docs: Returns the first WsByteBuffer set in 'writeCtx', ensuring that it is the sole byte buffer set in 'writeCtx', and
  releasing any other byte buffers that had been registered there.
  @return the sole byte buffer set in 'writeCtx'; maybe null if there is no such byte buffer.