code: public ByteBuffer getAttributeBuffer(int index) {
          final VertexAttribute attribute = getAttribute(index);
          if (attribute == null) {
              return null;
          }
          return attribute.getData();
      }
docs: Returns the buffer for the attribute at the provided index, or null if none can be found. The buffer is returned filled and ready for reading.
  
  @param index The index to lookup
  @return The attribute buffer, filled and flipped