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
/**
     * Returns the item before the given item in the tree, or <code>null</code>
     * if there is no previous item.
     * 
     * @param item
     *           the item
     * @return the previous item, or <code>null</code> if none
     */
    protected Item getPreviousItem(Item item) {
        
        
        Item parent = getParentItem(item);
        if (parent == null) {
            return null;
        }
        Item[] siblings = getItems(parent);
        if (siblings.length == 0 || siblings[0] == item) {
            return parent;
        }
        Item previous = siblings[0];
        for (int i = 1; i < siblings.length; i++) {
            if (siblings[i] == item) {
                return rightMostVisibleDescendent(previous);
            }
            previous = siblings[i];
        }
        return null;
    }
    
    protected Object[] getRawChildren(Object parent) {