Bug 122869 Drag a parameter from data explorer view into a table in library, a new parameter is created automatically.
Description:Drag a parameter from data explorer view into a table in library, a new parameter is created automatically. Steps to reproduce: 1. Add a cascading parameter and a table in a library file. 2. Drag a parameter from data explorer view into a table cell in layout editor. 3. Find that a new parameter was added in data explorer view automatically.
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/util/DEUtil.java
{
		if ( str1 == null && str2 == null )
		{
			return true;
		}
		if ( str1 != null && str1.equals( str2 ) )
		{
			return true;
		}
		return false;
	}
	/**
	 * Create a row expression base on column name.
	 * 
	 * @param columnName
	 * @return
	 */
	public static String getColumnExpression( String columnName )
	{
		Assert.isNotNull( columnName );
		if ( StringUtil.isBlank( columnName ) )
		{
			return null;
		}
		return IReportElementConstants.DATA_COLUMN_PREFIX
				+ "[\"" + DEUtil.escape( columnName ) + "\"]";
	}
	/**
	 * Relativizes the path against this base path.
	 *