Summary

Clarify JList.getScrollableUnitIncrement can return a non-negative value that is, a positive value including 0, instead of mentioning it will always return a positive number.

Problem

JList.getScrollableUnitIncrement specifies that it always returns positive number, which in certain cases is not correct, as it can return 0.

Solution

Update JList.getScrollableUnitIncrement to mention it will return a non-negative number comprising of either 0 or any positive number

Specification

javax.swing.JList

     * @return the "unit" increment for scrolling in the specified direction;
-     *         always positive
+     *         returns a non-negative value
+     *
      * @see #getScrollableBlockIncrement
public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction)