AnonymousConfigurerTests groovy->java

This test now checks key and principal both, which differs from the original Groovy test

In order to keep from needing to execute logic internal to `AnonymousAuthenticationToken`, this test changed from the original Groovy test. In the Groovy test, `key` is tested; however in this new test, `principal` is tested instead.

A concern was raised that if `AnonymousAuthenticationProvider` were invoked in this test, then testing only `principal` would not confirm that `key` was correctly propagated to `AnonymousAuthenticationProvider`. So, the test now configures both `key` and `principal`. The former to confirm correct wiring of `AnonymousAuthenticationProvider` and the latter to confirm correct wiring of `AnonymousAuthenticationFilter`.

Issue: gh-4939

config/src/test/java/org/springframework/security/config/annotation/web/configurers/AnonymousConfigurerTests.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2002-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.security.config.annotation.web.configurers;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.security.config.annotation.web.builders.HttpSecurity;
+import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
+import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
+import org.springframework.security.config.test.SpringTestRule;
+import org.springframework.security.core.annotation.AuthenticationPrincipal;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.servlet.config.annotation.EnableWebMvc;
+
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
+
+/**
+ * @author Rob Winch
+ * @author Josh Cummings
+ */
+public class AnonymousConfigurerTests {
+	@Rule
+	public final SpringTestRule spring = new SpringTestRule();
+
+	@Autowired
+	private MockMvc mockMvc;
+
+	@Test
+	public void requestWhenAnonymousTwiceInvokedThenDoesNotOverride() throws Exception {
+		this.spring.register(InvokeTwiceDoesNotOverride.class).autowire();
+
+		this.mockMvc.perform(get("/"))
+			.andExpect(content().string("principal"));
+	}
+
+	@EnableWebSecurity
+	@EnableWebMvc
+	static class InvokeTwiceDoesNotOverride extends WebSecurityConfigurerAdapter {
+
+		@Override
+		protected void configure(HttpSecurity http) throws Exception {
+			http
+				.anonymous()
+					.key("key")
+					.principal("principal")
+					.and()
+				.anonymous();
+		}
+
+		@RestController
+		static class PrincipalController {
+			@GetMapping("/")
+			String principal(@AuthenticationPrincipal String principal) {
+				return principal;
+			}
+		}
+	}
+}