@Override
  public void interceptInitializerMethod(IMethodInvocation invocation) throws Throwable {
    injectValues(invocation.getInstance(), false, (Specification)invocation.getInstance());
    invocation.proceed();
  }
Creates a Guice injector, and injects Guice-provided objects into specifications.

@author Peter Niederwieser
spock-guice/src/main/java/org/spockframework/guice/GuiceInterceptor.java