Bug 80429 [Preferences] [Dialogs] FieldEditors should relax requirements to support DialogPages
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/FieldEditor.java
/**
     * Property name constant (value <code>"field_editor_is_valid"</code>)
     * to signal a change in the validity of the value of this field editor.
     */
    public static final String IS_VALID = "field_editor_is_valid";
    /**
     * Property name constant (value <code>"field_editor_value"</code>)
     * to signal a change in the value of this field editor.
     */
    public static final String VALUE = "field_editor_value";