code: public WithStaticFinder<T> as(Object testDouble) throws FinderFieldNotFoundException {
  
      try {
        this.testDouble = testDouble;
  
        this.field = findField();
        this.field.setAccessible(true);
        try {
          Field modifiersField = Field.class.getDeclaredField("modifiers");
  
          /**
           * If the project using this library has a SecurityManager set up, permission may be denied.
           * Therefor, running this as a privileged action.
           */
          AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
              modifiersField.setAccessible(true);
              return null;
          });
  
          modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL);
        } catch (NoSuchFieldException e) {
          throw new RuntimeException(e);
        }
  
        this.original = field.get(null);
        return this;
  
      } catch (IllegalAccessException e) {
        throw new RuntimeException(e);
      }
    }
docs: Set the test double instance to use after useTestDouble() has been called.
  <p/>
  Note that the test double instance is not set until <code>useTestDouble()</code> is called.