Deprecate Guava support

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/cache/GuavaCacheStatisticsProvider.java

@@ -26,7 +26,9 @@ import org.springframework.cache.guava.GuavaCache;
  *
  * @author Stephane Nicoll
  * @since 1.3.0
+ * @deprecated as of 1.5 following the removal of Guava support in Spring Framework 5
  */
+@Deprecated
 public class GuavaCacheStatisticsProvider implements CacheStatisticsProvider<GuavaCache> {
 
 	@Override

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cache/CacheProperties.java

@@ -20,6 +20,7 @@ import java.util.ArrayList;
 import java.util.List;
 
 import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.boot.context.properties.DeprecatedConfigurationProperty;
 import org.springframework.core.io.Resource;
 import org.springframework.util.Assert;
 
@@ -266,10 +267,15 @@ public class CacheProperties {
 		 */
 		private String spec;
 
+		@Deprecated
+		@DeprecatedConfigurationProperty(
+				reason = "Caffeine will supersede the Guava support in Spring Boot 2.0",
+				replacement = "spring.cache.caffeine.spec")
 		public String getSpec() {
 			return this.spec;
 		}
 
+		@Deprecated
 		public void setSpec(String spec) {
 			this.spec = spec;
 		}

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cache/CacheType.java

@@ -69,6 +69,7 @@ public enum CacheType {
 	/**
 	 * Guava backed caching.
 	 */
+	@Deprecated
 	GUAVA,
 
 	/**

spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -3799,7 +3799,7 @@ providers (in this order):
 * <<boot-features-caching-provider-couchbase,Couchbase>>
 * <<boot-features-caching-provider-redis,Redis>>
 * <<boot-features-caching-provider-caffeine,Caffeine>>
-* <<boot-features-caching-provider-guava,Guava>>
+* <<boot-features-caching-provider-guava,Guava>> (deprecated)
 * <<boot-features-caching-provider-simple,Simple>>
 
 TIP: It is also possible to _force_ the cache provider to use via the `spring.cache.type`
@@ -4019,7 +4019,7 @@ auto-configuration.
 
 
 [[boot-features-caching-provider-guava]]
-==== Guava
+==== Guava (deprecated)
 If Guava is present, a `GuavaCacheManager` is auto-configured. Caches can be created
 on startup using the `spring.cache.cache-names` property and customized by one of the
 following (in this order):