Make OAuth2TokenIntrospectionEndpointConfigurer.getRequestMatcher() package-private

Closes gh-824

oauth2-authorization-server/src/main/java/org/springframework/security/oauth2/server/authorization/config/annotation/web/configurers/OAuth2TokenIntrospectionEndpointConfigurer.java

@@ -145,7 +145,7 @@ public final class OAuth2TokenIntrospectionEndpointConfigurer extends AbstractOA
 	}
 
 	@Override
-	public RequestMatcher getRequestMatcher() {
+	RequestMatcher getRequestMatcher() {
 		return this.requestMatcher;
 	}