Bug 123406 Add geLocaltStringProperty in GroupElementHandle and GroupPropertyHandle
Please refer to 123405. GUI need a way to get the local setting of given property because current getStringPropery method will return inherited value if there are no local value.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/SimpleGroupElementHandle.java
List rtnPropDefns = Collections.EMPTY_LIST;
		for ( int j = 0; j < elements.size( ); j++ )
		{
			Object item = elements.get( j );
			if ( !( item instanceof DesignElementHandle ) )
				return Collections.EMPTY_LIST;
			List propDefns = ( (DesignElementHandle) item ).getElement( )
					.getPropertyDefns( );
			if ( propDefns.size( ) < min )
			{
				min = propDefns.size( );
				rtnPropDefns = propDefns;
			}
		}
		return rtnPropDefns;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.api.GroupElementHandle#isSameType()
	 */
	public boolean isSameType( )
	{
		if ( elements.size( ) == 0 )
			return false;
		IElementDefn baseDefn = null;
		for ( int i = 0; i < elements.size( ); i++ )
		{
			Object item = elements.get( i );
			if ( !( item instanceof DesignElementHandle ) )