Bug 144522 [Field Assist] - should proposal popup ever open if empty?
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
IContentProposalProvider proposalProvider) {
		this.proposalProvider = proposalProvider;
	}
	/**
	 * Return the array of characters on which the popup is autoactivated.
	 * 
	 * @return An array of characters that trigger auto-activation of content
	 *         proposal. If specified, these characters will trigger
	 *         auto-activation of the proposal popup, regardless of whether an
	 *         explicit invocation keyStroke was specified. If this parameter is
	 *         <code>null</code>, then only a specified keyStroke will invoke
	 *         content proposal. If this value is <code>null</code> and the
	 *         keyStroke value is <code>null</code>, then all alphanumeric
	 *         characters will auto-activate content proposal.
	 */
	public char[] getAutoActivationCharacters() {
		if (autoActivateString == null) {
			return null;
		}
		return autoActivateString.toCharArray();
	}
	/**
	 * Set the array of characters that will trigger autoactivation of the
	 * popup.
	 * 
	 * @param autoActivationCharacters
	 *            An array of characters that trigger auto-activation of content
	 *            proposal. If specified, these characters will trigger
	 *            auto-activation of the proposal popup, regardless of whether
	 *            an explicit invocation keyStroke was specified. If this