Deprecate SecurityPrerequisite

Deprecate `SecurityPrerequisite` interface since we don't support it
in Spring Boot 2.

Closes gh-14846

Author: philwebb

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/web/server/ManagementServerProperties.java

@@ -18,7 +18,6 @@
 
 import java.net.InetAddress;
 
-import org.springframework.boot.autoconfigure.security.SecurityPrerequisite;
 import org.springframework.boot.autoconfigure.web.ServerProperties;
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.context.properties.NestedConfigurationProperty;
@@ -36,7 +35,7 @@
  * @see ServerProperties
  */
 @ConfigurationProperties(prefix = "management.server", ignoreUnknownFields = true)
-public class ManagementServerProperties implements SecurityPrerequisite {
+public class ManagementServerProperties {
 
 	/**
 	 * Management endpoint HTTP port (uses the same port as the application by default).

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/SecurityPrerequisite.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -21,7 +21,9 @@
  * configuration is evaluated.
  *
  * @author Dave Syer
+ * @deprecated since 2.0.6 since security prerequisites are not supported in Spring Boot 2
  */
+@Deprecated
 public interface SecurityPrerequisite {
 
 }

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/SecurityProperties.java

@@ -37,7 +37,7 @@
  * @author Madhura Bhave
  */
 @ConfigurationProperties(prefix = "spring.security")
-public class SecurityProperties implements SecurityPrerequisite {
+public class SecurityProperties {
 
 	/**
 	 * Order applied to the WebSecurityConfigurerAdapter that is used to configure basic