core/src/com/google/inject/internal/Annotations.java
public static <T extends Annotation> T generateAnnotation(Class<T> annotationType) {
    Preconditions.checkState(
        isAllDefaultMethods(annotationType), "%s is not all default methods", annotationType);
    return (T) cache.getUnchecked(annotationType);
  }
public static <T extends Annotation> T generateAnnotation(Class<T> annotationType) {
    Preconditions.checkState(
        isAllDefaultMethods(annotationType), "%s is not all default methods", annotationType);
    return (T) cache.getUnchecked(annotationType);
  }
Generates an Annotation for the annotation class. Requires that the annotation is all
optionals.