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/preference/StringFieldEditor.java
}
    /* (non-Javadoc)
     * Method declared on FieldEditor.
     */
    public boolean isValid() {
        return isValid;
    }
    /* (non-Javadoc)
     * Method declared on FieldEditor.
     */
    protected void refreshValidState() {
        isValid = checkState();
    }
    /**
     * Sets whether the empty string is a valid value or not.
     *
     * @param b <code>true</code> if the empty string is allowed,
     *  and <code>false</code> if it is considered invalid
     */
    public void setEmptyStringAllowed(boolean b) {
        emptyStringAllowed = b;
    }
    /**
     * Sets the error message that will be displayed when and if 
     * an error occurs.
     *
     * @param message the error message
     */
    public void setErrorMessage(String message) {
        errorMessage = message;