Bug 92988 [Viewers] potential NPE in AbstractTreeViewer
I0426, found with FindBugs 1. AbstractTreeViewer line 832 invokes "siblings.length", but the "if" statement above implies that siblings could be null here. 2. StringFieldEditor line 187 does an unnecessary null check since Text.getText() never returns null (FindBugs was using this to point to line 190 as a potential NPE).
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
* Sets the auto-expand level. The value 0 means that there is no
     * auto-expand; 1 means that top-level elements are expanded, but not their
     * children; 2 means that top-level elements are expanded, and their
     * children, but not grandchildren; and so on.
     * <p>
     * The value <code>ALL_LEVELS</code> means that all subtrees should be
     * expanded.
     * </p>
     * 
     * @param level
     *           non-negative level, or <code>ALL_LEVELS</code> to expand all
     *           levels of the tree
     */
    public void setAutoExpandLevel(int level) {
        expandToLevel = level;
    }
    /**
     * The <code>AbstractTreeViewer</code> implementation of this method
     * checks to ensure that the content provider is an <code>ITreeContentProvider</code>.
     */
    public void setContentProvider(IContentProvider provider) {
        Assert.isTrue(provider instanceof ITreeContentProvider);
        super.setContentProvider(provider);
    }
    /**
     * Sets the expand state of the given item.
     * 
     * @param item
     *           the item
     * @param expand