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 (root.isArchive() && getFlag(flags, ROOT_VARIABLE)) {
			try {
				IClasspathEntry rawEntry= root.getRawClasspathEntry();
				if (rawEntry != null) {
					if (rawEntry.getEntryKind() == IClasspathEntry.CPE_VARIABLE) {
						buf.append(rawEntry.getPath().makeRelative());
						buf.append(CONCAT_STRING);
					}
				}
			} catch (JavaModelException e) {
				JavaPlugin.log(e); 
			}
		}
		if (root.isExternal()) {
			
			
			buf.append(root.getPath().toOSString());
		} else {
			if (getFlag(flags, ROOT_QUALIFIED)) {
				buf.append(root.getPath().makeRelative().toString());
			} else {
				buf.append(root.getElementName());
			}
			if (getFlag(flags, ROOT_POST_QUALIFIED)) {
				buf.append(CONCAT_STRING);
				buf.append(root.getParent().getElementName());
			}
		}		
	}	
	private static void refreshPackageNamePattern() {