Bug 145022 Provide a utility method to help GUI enhance aggregate on.
DtE will provide a method hasAggregation(String expression) in org.eclipse.birt.core.data.ExpressionUtil, and the return value will be true when the expression is a valid JS expression and it has aggregation defined.
core/org.eclipse.birt.core/src/org/eclipse/birt/core/data/ExpressionUtil.java
if ( oldExpression == null )
			return new ArrayList( );
		List exprList = ExpressionParserUtility.compileColumnExpression( oldExpression );
		for ( int i = 0; i < exprList.size( ); )
		{
			IColumnBinding info = (IColumnBinding) exprList.get( i );
			if ( info.getOuterLevel( ) != 0 )
			{
				exprList.remove( i );
			}
			else
				i++;
		}
		return exprList;
	}
	
	/**
     * extract all column expression info, including outer_level >0 
	 * @param oldExpression
	 * @return
	 * @throws BirtException
	 */
	public static List extractColumnInfo( String oldExpression )
			throws BirtException
	{
		if ( oldExpression == null )
			return new ArrayList( );
		return ExpressionParserUtility.compileColumnExpression( oldExpression );
	}
	/**