Bug 165278 this.getDisplayContent()="" in script of text will destroy preview[0801]
Description: this.getDisplayContent()="" in script of text will destroy preview Build number:2.1.2.v20061120 and 2.2.0.v20061117 Steps to reproduce: 1. Insert a text item, select it and switch to script editor 2. Input this.getDisplayContent()="" and preview Expected result: Error message about the incorrect script. Actual result: In 2.1.2, I saw HTTP Status 500 - type Exception report message description The server encountered an internal error () that prevented it from fulfilling this request. In 2.2.0, I saw error dialog with java.lang.ClassCastException.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/executor/ExecutionContext.java
{
		private static String[] classPathes = new String[]{
				EngineConstants.WEBAPP_CLASSPATH_KEY,
				EngineConstants.PROJECT_CLASSPATH_KEY,
				EngineConstants.WORKSPACE_CLASSPATH_KEY};
		private ExecutionContext context = null;
		private ClassLoader loader = null;
		public ApplicationClassLoader( ExecutionContext context )
		{
			this.context = context;
		}
		public Class loadClass( String className )
				throws ClassNotFoundException
		{
			try
			{
				return Class.forName( className );
			}
			catch ( ClassNotFoundException ex )
			{
				if ( loader == null )
				{
					createWrappedClassLoaders( );