Bug 135490 Error occurs when Preview Results of Inner Join datasets
Description: Create a sample datasource and dataset, and then create a Joint dataset. Error occurs when preview results in the data set dialog. Steps to reproduce: 1.Create a sample datasource, and a dataset with sql statement "select * from CLASSICMODELS.CUSTOMERS". 2.Create a Joint dataset, the left and right dataset is the same. 3.Preview result in the dataset dialog, error pops up continuely.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/jointdataset/JoinConditionMatcher.java
{
	
	private JoinConditionMatchUnit[] left = new JoinConditionMatchUnit[0];
	private JoinConditionMatchUnit[] right = new JoinConditionMatchUnit[0];
	
	/**
	 * Constructor.
	 * 
	 * @param leftRi
	 * @param rightRi
	 * @param leftScope
	 * @param rightScope
	 * @param joinConditions
	 */
	public JoinConditionMatcher( IResultIterator leftRi, IResultIterator rightRi, Scriptable leftScope, Scriptable rightScope, List joinConditions)
	{
		this.left = new JoinConditionMatchUnit[joinConditions.size( )];
		this.right = new JoinConditionMatchUnit[joinConditions.size( )];
		
		Context cx = Context.enter( );
		for( int i = 0; i < joinConditions.size( ); i++ )
		{