PluginParameterExpressionEvaluator incorrectly interpolates unknown subexpression

        if ( value instanceof String )
        {
            // TODO: without #, this could just be an evaluate call...
            String val = (String) value;
            int exprStartDelimiter = val.indexOf( "${" );
            if ( exprStartDelimiter >= 0 )
            {
                if ( exprStartDelimiter > 0 )
                {
                    value = val.substring( 0, exprStartDelimiter ) + evaluate( val.substring( exprStartDelimiter ) );
                }
                else
                {
                    value = evaluate( val.substring( exprStartDelimiter ) );
                }
            }
        }