Bug 186403 [KeyBindings] provide conflict information to users outside of logging
bundles/org.eclipse.jface/src/org/eclipse/jface/bindings/CachedBindingSet.java
*            of available completions (possibly <code>null</code>, which
	 *            means there is an exact match). The available completions is a
	 *            map of trigger (<code>TriggerSequence</code>) to command
	 *            identifier (<code>String</code>). Must not be
	 *            <code>null</code>.
	 */
	final void setPrefixTable(final Map prefixTable) {
		if (prefixTable == null) {
			throw new NullPointerException("Cannot set a null prefix table"); 
		}
		this.prefixTable = prefixTable;
	}
	/**
	 * Sets the map of triggers indexed by command identifiers.
	 * 
	 * @param triggersByCommandId
	 *            The map to set; must not be <code>null</code>. This is a
	 *            map of command identifiers (<code>String</code>) to
	 *            triggers (<code>Collection</code> of
	 *            <code>TriggerSequence</code>).
	 */
	final void setTriggersByCommandId(final Map triggersByCommandId) {
		if (triggersByCommandId == null) {
			throw new NullPointerException(
					"Cannot set a null binding resolution"); 
		}
		this.triggersByCommandId = triggersByCommandId;
	}
}