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
/**
	 * Method names contain parameter types.
	 * e.g. <code>foo(int)</code>
	 */
	public final static int M_PARAMETER_TYPES= 1 << 0;
	
	/**
	 * Method names contain parameter names.
	 * e.g. <code>foo(index)</code>
	 */
	public final static int M_PARAMETER_NAMES= 1 << 1;	
	
	/**
	 * Method names contain thrown exceptions.
	 * e.g. <code>foo throws IOException</code>
	 */
	public final static int M_EXCEPTIONS= 1 << 2;
	
	/**
	 * Method names contain return type (appended)
	 * e.g. <code>foo : int</code>
	 */
	public final static int M_APP_RETURNTYPE= 1 << 3;