Issue #6166 - fix bug in the MessageInputStream byte array read

[lachlan-roberts]

Issue #6166

The code for MessageInputStream.read(final byte[] b, final int off, final int len) seems to be wrong. Instead of doing ByteBuffer.wrap(b, off, len).flip() we should do something like:

ByteBuffer buffer = ByteBuffer.wrap(b, off, len).slice();
BufferUtil.clear(buffer);
return read(buffer);

This will ensure that the buffer we get to represent the byte array always has a position and limit of 0, an offset of off, and a capacity of len.

The only time when MessageInputStream.read(ByteBuffer) will compact is when the buffer already has content and limit == capacity. So if we make this change, a call to MessageInputStream.read(final byte[] b, final int off, final int len) will never compact as the buffer is always empty with position == limit.