Singleton to end all singletons

Global.java

package common;

import java.util.HashMap;
import java.util.Map;

public class Global {
    private static boolean inTests;
    private static final Map<Class<?>, Object> globals = new HashMap<Class<?>, Object>();

    private Global() {}
    
    public static <T> void initializeInstance(Class<T> type, T global) {
        if (globals.containsKey(type) && !inTests)
            throw new IllegalArgumentException("This global is already initialized:" + type);
        globals.put(type, global);
    }
    
    public static <T> T getInstance(Class<T> type) {
        if (!globals.containsKey(type))
            throw new IllegalArgumentException("Not a global: " + type);
        return type.cast(globals.get(type));
    }
    
    public static void ISolemnlySwearIAmInATest() {
        inTests = true;
    }
}