@Override
            public void write(IApimanBuffer buffer) {
                if (streamFinished) {
                    throw new IllegalStateException("Attempted write after #end() was called."); //$NON-NLS-1$
                }
                requestChain.write(buffer);
            }
Called when the api connector is ready to receive data from the inbound
client request.
gateway/engine/core/src/main/java/io/apiman/gateway/engine/impl/ApiRequestExecutorImpl.java