public Object proceed() throws Throwable {
        // Do nothing since this adapts a before advice
        return null;
    }
Factory method that creates a new {@link BeforeAdviceMethodInvocationAdapter} instance
using the AspectJ {@link JoinPoint} provided. If the joint point passed in is not
a method joint point, this method throws an {@link IllegalArgumentException}.

@param aJoinPoint The AspectJ {@link JoinPoint} to use to adapt the advice.
@return The created instance.
@throws IllegalArgumentException If the join point passed in does not involve a method call.
support/aspectj/src/main/java/org/apache/shiro/aspectj/BeforeAdviceMethodInvocationAdapter.java