Bug 16858 Preceding space in package compression pattern sometimes ignored
(In the following discussion, all patterns were entered without the enclosing quote marks.) The pattern "1 " causes one character of each package name to be displayed with a single space separator between them. The pattern " 1 " causes one space to precede the first single-character package name and two spaces to appear between each one. Both of the above cases were expected. However, if you set the patttern to " 1" (i.e. space before, but no space after), no spaces are displayed in the result.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/viewsupport/JavaElementLabels.java
if (declaration.getElementType() == IJavaElement.IMPORT_CONTAINER) {
			buf.append(JavaUIMessages.getString("JavaElementLabels.import_container")); 
		} else {
			buf.append(declaration.getElementName());
		}
		
		if (getFlag(flags, D_POST_QUALIFIED)) {
			IJavaElement openable= (IJavaElement) declaration.getOpenable();
			if (openable != null) {
				buf.append(CONCAT_STRING);
				buf.append(getElementLabel(openable, CF_QUALIFIED | CU_QUALIFIED));
			}				
		}
	}	
	
	/**
	 * Appends the label for a class file to a StringBuffer. Considers the CF_* flags.
	 */	
	public static void getClassFileLabel(IClassFile classFile, int flags, StringBuffer buf) {
		if (getFlag(flags, CF_QUALIFIED)) {
			IPackageFragment pack= (IPackageFragment) classFile.getParent();
			if (!pack.isDefaultPackage()) {
				buf.append(pack.getElementName());
				buf.append('.');
			}
		}
		buf.append(classFile.getElementName());
		
		if (getFlag(flags, CF_POST_QUALIFIED)) {
			buf.append(CONCAT_STRING);