Bug 6410 File unchanged but dirtied by code assist
1122. Open a Java file. Place the cursor inside the left-most parenthesis of a method call. For example, consider "I" to be the cursor below: Object o = anotherObject.method(I); Press Ctrl-Space. The file is dirtied but not changed, and code assist does not appear. If code assist has nothing to suggest, it should not dirty the file.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/java/JavaCompletionProposal.java
* @param triggerCharacters The set of characters which can trigger the application of this completion proposal
	 */
	public void setTriggerCharacters(char[] triggerCharacters) {
		fTriggerCharacters= triggerCharacters;
	}
	
	/**
	 * Sets the proposal info.
	 * @param additionalProposalInfo The additional information associated with this proposal or <code>null</code>
	 */
	public void setProposalInfo(ProposalInfo proposalInfo) {
		fProposalInfo= proposalInfo;
	}
	
	/**
	 * Sets the cursor position relative to the insertion offset. By default this is the length of the completion string
	 * (Cursor positioned after the completion)
	 * @param cursorPosition The cursorPosition to set
	 */
	public void setCursorPosition(int cursorPosition) {
		Assert.isTrue(cursorPosition >= 0);
		fCursorPosition= cursorPosition;
		fContextInformationPosition= (fContextInformation != null ? fCursorPosition : -1);
	}	
	
	protected void applyImports(IDocument document) {
		if (fImportDeclaration == null) {
			return;
		}