Bug 13034 Cannot create a Source Folder in a new Java Project
build 20020404 If you try and create a Source Folder in a Java Project you have just created you get an error preventing you from hitting finish. STEPS 1) Create Java Project Foo 2) Open New->Source Folder 3) Enter Bar as the name - you will get "Cannot nest entry Bar inside entry Foo/Bar" 4) Create a folder Bar. 5) Add it as a source folder in the Properties Dialog for Foo. No problem.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/BuildPathsBlock.java
String[] buttonLabels= new String[] {
			 NewWizardMessages.getString("BuildPathsBlock.classpath.up.button"), 
			 NewWizardMessages.getString("BuildPathsBlock.classpath.down.button"), 
			 null,
			 NewWizardMessages.getString("BuildPathsBlock.classpath.checkall.button"), 
			 NewWizardMessages.getString("BuildPathsBlock.classpath.uncheckall.button") 
		
		};
		
		fClassPathList= new CheckedListDialogField(null, buttonLabels, new CPListLabelProvider());
		fClassPathList.setDialogFieldListener(adapter);
		fClassPathList.setLabelText(NewWizardMessages.getString("BuildPathsBlock.classpath.label"));  
		fClassPathList.setUpButtonIndex(0);
		fClassPathList.setDownButtonIndex(1);
		fClassPathList.setCheckAllButtonIndex(3);
		fClassPathList.setUncheckAllButtonIndex(4);		
			
		fBuildPathDialogField= new StringButtonDialogField(adapter);
		fBuildPathDialogField.setButtonLabel(NewWizardMessages.getString("BuildPathsBlock.buildpath.button")); 
		fBuildPathDialogField.setDialogFieldListener(adapter);
		fBuildPathDialogField.setLabelText(NewWizardMessages.getString("BuildPathsBlock.buildpath.label")); 
		fBuildPathStatus= new StatusInfo();
		fClassPathStatus= new StatusInfo();
		
		fCurrJProject= null;
	}