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
try {
			
			if (getFlag(flags, M_PRE_RETURNTYPE) && method.exists() && !method.isConstructor()) {
				buf.append(Signature.getSimpleName(Signature.toString(method.getReturnType())));
				buf.append(' ');
			}
			
			
			if (getFlag(flags, M_FULLY_QUALIFIED)) {
				getTypeLabel(method.getDeclaringType(), T_FULLY_QUALIFIED, buf);
				buf.append('.');
			}
				
			buf.append(method.getElementName());
			
			
			if (getFlag(flags, M_PARAMETER_TYPES | M_PARAMETER_NAMES)) {
				buf.append('(');
				
				String[] types= getFlag(flags, M_PARAMETER_TYPES) ? method.getParameterTypes() : null;
				String[] names= (getFlag(flags, M_PARAMETER_NAMES) && method.exists()) ? method.getParameterNames() : null;
				int nParams= types != null ? types.length : names.length;
				
				for (int i= 0; i < nParams; i++) {
					if (i > 0) {
						buf.append(COMMA_STRING); 
					}
					if (types != null) {
						buf.append(Signature.getSimpleName(Signature.toString(types[i])));
					}