Bug 123523 Previewing a scripted data set mapped to a java event handler throws NPE
When previewing a scripted data set we try to get a class loader from the ExecutionContext. (See ScriptExecutor.getClassUsingCustomClassPath). The context will be null in this case. The reason for using the context is to use cached class loaders when possible. Need to use some other mechanism to get the class loader if the context is null. We can either provide an external map to use as cache, or not bother with caching at all.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/executor/ExecutionContext.java
/**
	 * is in factory mode
	 * 
	 * @return true, factory mode, false not in factory mode
	 */
	public boolean isInFactory( )
	{
		return factoryMode;
	}
	/**
	 * is in presentation mode.
	 * 
	 * @return true, presentation mode, false otherwise
	 */
	public boolean isInPresentation( )
	{
		return presentationMode;
	}
	/**
	 * set the in factory mode
	 * 
	 * @param mode
	 *            factory mode
	 */
	public void setFactoryMode( boolean mode )
	{
		this.factoryMode = mode;
	}
	/**
	 * set in presentation mode