The code still contains concepts that were used long before Java 8 in many places. Some of these can or should now be replaced by other constructs.

Some classes (AbstractSVGLengthList, AbstractSVGNumberList, AbstractSVGPathSegList, ...) use create methods for throwables but miss to throw them.

@Override
protected void checkItemType(Object newItem) throws SVGException {
  if (!(newItem instanceof SVGLength)) {
    createSVGException(SVGException.SVG_WRONG_TYPE_ERR, "expected.length", null);
  }
}

However, throwing throwables can now lead to a completely different behavior of the implementation.