in runner-core/src/main/java/org/apache/apisix/plugin/runner/handler/PayloadDecoder.java [115:122]
private ByteBuffer getBody(ByteBuffer payload) throws BufferUnderflowException, IndexOutOfBoundsException {
int length = getDataLength(payload);
ByteBuffer buffer = payload.slice();
byte[] dst = new byte[length];
buffer.get(dst, 0, length);
buffer.flip();
return buffer;
}