A security expression handler that can handle default method security expressions plus the set provided by {@link OAuth2SecurityExpressionMethods} using the variable oauth2 to access the methods. For example, the expression#oauth2.clientHasRole('ROLE_ADMIN')
would invoke {@link OAuth2SecurityExpressionMethods#clientHasRole}
By default the {@link OAuth2ExpressionParser} is used. If this is undesirable one can inject their own{@link ExpressionParser} using {@link #setExpressionParser(ExpressionParser)}.
@author Dave Syer
@author Rob Winch
@see OAuth2ExpressionParser