Error in TextureData?

I am using Texture.updateSubImage(…) to update a region of a texture with the content of a TextureData object.
Internally this method is calling “gl.glPixelStorei(GL.GL_UNPACK_ROW_LENGTH, rowlen);” to be able to update only a region.
The update goes wrong as rowlen coming from TextureData.getRowLength() is not set (0 by default).

The TextureData is not loaded from an image but created using the constructor with a Buffer, width, height, etc.
Therefore rowLength inside TextureData is not set, which is done automatically if you load an existing image.

After setting the row length manually on TextureData it works as expected.

Does anybody know if this is by purpose or just an error?