Bug 43488 [typing] BadPositionCategoryException in LinkedPositionManager
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/link/contentassist/ContentAssistant2.java
IContextInformationPresenter getContextInformationPresenter(ITextViewer textViewer, int offset) {
		IContextInformationValidator validator= getContextInformationValidator(textViewer, offset);
		if (validator instanceof IContextInformationPresenter)
			return (IContextInformationPresenter) validator;
		return null;
	}
	
	/**
	 * Returns the characters which when typed by the user should automatically
	 * initiate proposing completions. The position is used to determine the 
	 * appropriate content assist processor to invoke.
	 *
	 * @param textViewer the text viewer
	 * @param offset a document offset
	 * @return the auto activation characters
	 *
	 * @see IContentAssistProcessor#getCompletionProposalAutoActivationCharacters
	 */
	private char[] getCompletionProposalAutoActivationCharacters(ITextViewer textViewer, int offset) {
		IContentAssistProcessor p= getProcessor(textViewer, offset);
		return p != null ? p.getCompletionProposalAutoActivationCharacters() : null;
	}
	
	/**
	 * Returns the characters which when typed by the user should automatically
	 * initiate the presentation of context information. The position is used
	 * to determine the appropriate content assist processor to invoke.
	 *
	 * @param textViewer the text viewer
	 * @param offset a document offset