Bug 152430 Key can modify to empty string
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/CustomColorHandle.java
* Returns the internal display name.
	 * 
	 * @return the internal display name
	 */
	public String getDisplayName( )
	{
		return getStringProperty( CustomColor.DISPLAY_NAME_MEMBER );
	}
	/**
	 * Sets the display name.
	 * 
	 * @param displayName
	 *            the display name to set
	 */
	public void setDisplayName( String displayName )
	{
		setPropertySilently( CustomColor.DISPLAY_NAME_MEMBER, displayName );
	}
	/**
	 * Returns the resource key for display name.
	 * 
	 * @return the resource key for display name.
	 */
	public String getDisplayNameID( )
	{
		return getStringProperty( CustomColor.DISPLAY_NAME_ID_MEMBER );
	}
	/**
	 * Sets the resource key for display name.
	 *