docs: @Nonnull
  	public <N> byte[] buildCompositeKeyNamespace(@Nonnull N namespace, @Nonnull TypeSerializer<N> namespaceSerializer) {
  		try {
  			serializeNamespace(namespace, namespaceSerializer);
  			final byte[] result = keyOutView.getCopyOfBuffer();
  			resetToKey();
  			return result;
  		} catch (IOException shouldNeverHappen) {
  			throw new FlinkRuntimeException(shouldNeverHappen);
  		}
  	}