Method drain

output/java_guava/1.4.16/ReaderInputStream.java:248–252

Copy as much of the byte buffer into the output array as possible, returning the (positive) number of characters copied.

(byte[] b, int off, int len)

   */

  private int drain(byte[] b, int off, int len) {
    int remaining = Math.min(len, byteBuffer.remaining());
    byteBuffer.get(b, off, remaining);
    return remaining;
  }
}