Bug 197589 Need constant for automaic attribute name "DateTime"
Currently when set dateTimeLevelType for cube level, model will automatically create a built-in attribute "DateTime". But the name is hard-coded. We need a public constant for this name to allow UI to access it.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/command/PropertyCommand.java
try
		{
			
			if ( contents != null )
			{
				for ( int i = 0; i < contents.size( ); i++ )
				{
					DesignElement content = (DesignElement) contents.get( i );
					cmd.remove( content );
				}
			}
			
			if ( value instanceof DesignElement )
			{
				cmd.add( (DesignElement) value );
			}
			else if ( value instanceof DesignElementHandle )
			{
				cmd.add( ( (DesignElementHandle) value ).getElement( ) );
			}
			else if ( value instanceof List )
			{
				contents = (List) value;
				for ( int i = 0; i < contents.size( );i++ )
				{
					Object item = contents.get( i );
					if ( item instanceof DesignElement )
					{
						cmd.add( (DesignElement) item );
					}