Fix overridden methods nullability

Issue: SPR-15869

spring-context-support/src/main/java/org/springframework/cache/caffeine/CaffeineCache.java

@@ -83,6 +83,7 @@ public class CaffeineCache extends AbstractValueAdaptingCache {
 	}
 
 	@Override
+	@Nullable
 	public ValueWrapper get(Object key) {
 		if (this.cache instanceof LoadingCache) {
 			Object value = ((LoadingCache<Object, Object>) this.cache).get(key);

spring-context-support/src/main/java/org/springframework/cache/caffeine/CaffeineCacheManager.java

@@ -176,6 +176,7 @@ public class CaffeineCacheManager implements CacheManager {
 	}
 
 	@Override
+	@Nullable
 	public Cache getCache(String name) {
 		Cache cache = this.cacheMap.get(name);
 		if (cache == null && this.dynamic) {

spring-context-support/src/main/java/org/springframework/cache/ehcache/EhCacheCache.java

@@ -64,6 +64,7 @@ public class EhCacheCache implements Cache {
 	}
 
 	@Override
+	@Nullable
 	public ValueWrapper get(Object key) {
 		Element element = lookup(key);
 		return toValueWrapper(element);
@@ -125,6 +126,7 @@ public class EhCacheCache implements Cache {
 	}
 
 	@Override
+	@Nullable
 	public ValueWrapper putIfAbsent(Object key, @Nullable Object value) {
 		Element existingElement = this.cache.putIfAbsent(new Element(key, value));
 		return toValueWrapper(existingElement);

spring-context-support/src/main/java/org/springframework/cache/ehcache/EhCacheFactoryBean.java

@@ -287,6 +287,7 @@ public class EhCacheFactoryBean extends CacheConfiguration implements FactoryBea
 
 
 	@Override
+	@Nullable
 	public Ehcache getObject() {
 		return this.cache;
 	}

spring-context-support/src/main/java/org/springframework/cache/ehcache/EhCacheManagerFactoryBean.java

@@ -169,6 +169,7 @@ public class EhCacheManagerFactoryBean implements FactoryBean<CacheManager>, Ini
 
 
 	@Override
+	@Nullable
 	public CacheManager getObject() {
 		return this.cacheManager;
 	}

spring-context-support/src/main/java/org/springframework/cache/jcache/JCacheCache.java

@@ -76,6 +76,7 @@ public class JCacheCache extends AbstractValueAdaptingCache {
 	}
 
 	@Override
+	@Nullable
 	public <T> T get(Object key, Callable<T> valueLoader) {
 		try {
 			return this.cache.invoke(key, new ValueLoaderEntryProcessor<T>(), valueLoader);
@@ -91,6 +92,7 @@ public class JCacheCache extends AbstractValueAdaptingCache {
 	}
 
 	@Override
+	@Nullable
 	public ValueWrapper putIfAbsent(Object key, @Nullable Object value) {
 		boolean set = this.cache.putIfAbsent(key, toStoreValue(value));
 		return (set ? null : get(key));

spring-context-support/src/main/java/org/springframework/cache/jcache/JCacheManagerFactoryBean.java

@@ -85,6 +85,7 @@ public class JCacheManagerFactoryBean
 
 
 	@Override
+	@Nullable
 	public CacheManager getObject() {
 		return this.cacheManager;
 	}

spring-context-support/src/main/java/org/springframework/cache/transaction/TransactionAwareCacheDecorator.java

@@ -72,6 +72,7 @@ public class TransactionAwareCacheDecorator implements Cache {
 	}
 
 	@Override
+	@Nullable
 	public ValueWrapper get(Object key) {
 		return this.targetCache.get(key);
 	}
@@ -82,6 +83,7 @@ public class TransactionAwareCacheDecorator implements Cache {
 	}
 
 	@Override
+	@Nullable
 	public <T> T get(Object key, Callable<T> valueLoader) {
 		return this.targetCache.get(key, valueLoader);
 	}
@@ -102,6 +104,7 @@ public class TransactionAwareCacheDecorator implements Cache {
 	}
 
 	@Override
+	@Nullable
 	public ValueWrapper putIfAbsent(Object key, @Nullable Object value) {
 		return this.targetCache.putIfAbsent(key, value);
 	}

spring-context-support/src/main/java/org/springframework/cache/transaction/TransactionAwareCacheManagerProxy.java

@@ -76,6 +76,7 @@ public class TransactionAwareCacheManagerProxy implements CacheManager, Initiali
 
 
 	@Override
+	@Nullable
 	public Cache getCache(String name) {
 		Assert.state(this.targetCacheManager != null, "No target CacheManager set");
 		Cache targetCache = this.targetCacheManager.getCache(name);

spring-context-support/src/main/java/org/springframework/mail/MailSendException.java

@@ -123,6 +123,7 @@ public class MailSendException extends MailException {
 
 
 	@Override
+	@Nullable
 	public String getMessage() {
 		if (ObjectUtils.isEmpty(this.messageExceptions)) {
 			return super.getMessage();

spring-context-support/src/main/java/org/springframework/scheduling/commonj/TimerManagerFactoryBean.java

@@ -110,6 +110,7 @@ public class TimerManagerFactoryBean extends TimerManagerAccessor
 	//---------------------------------------------------------------------
 
 	@Override
+	@Nullable
 	public TimerManager getObject() {
 		return getTimerManager();
 	}

spring-context-support/src/main/java/org/springframework/scheduling/commonj/TimerManagerTaskScheduler.java

@@ -56,6 +56,7 @@ public class TimerManagerTaskScheduler extends TimerManagerAccessor implements T
 
 
 	@Override
+	@Nullable
 	public ScheduledFuture<?> schedule(Runnable task, Trigger trigger) {
 		return new ReschedulingTimerListener(errorHandlingTask(task, true), trigger).schedule();
 	}

spring-context-support/src/main/java/org/springframework/scheduling/quartz/CronTriggerFactoryBean.java

@@ -266,6 +266,7 @@ public class CronTriggerFactoryBean implements FactoryBean<CronTrigger>, BeanNam
 
 
 	@Override
+	@Nullable
 	public CronTrigger getObject() {
 		return this.cronTrigger;
 	}

spring-context-support/src/main/java/org/springframework/scheduling/quartz/JobDetailFactoryBean.java

@@ -218,6 +218,7 @@ public class JobDetailFactoryBean
 
 
 	@Override
+	@Nullable
 	public JobDetail getObject() {
 		return this.jobDetail;
 	}

spring-context-support/src/main/java/org/springframework/scheduling/quartz/MethodInvokingJobDetailFactoryBean.java

@@ -223,6 +223,7 @@ public class MethodInvokingJobDetailFactoryBean extends ArgumentConvertingMethod
 
 
 	@Override
+	@Nullable
 	public JobDetail getObject() {
 		return this.jobDetail;
 	}

spring-context-support/src/main/java/org/springframework/scheduling/quartz/SchedulerFactoryBean.java

@@ -708,6 +708,7 @@ public class SchedulerFactoryBean extends SchedulerAccessor implements FactoryBe
 	}
 
 	@Override
+	@Nullable
 	public Scheduler getObject() {
 		return this.scheduler;
 	}

spring-context-support/src/main/java/org/springframework/scheduling/quartz/SimpleTriggerFactoryBean.java

@@ -251,6 +251,7 @@ public class SimpleTriggerFactoryBean implements FactoryBean<SimpleTrigger>, Bea
 
 
 	@Override
+	@Nullable
 	public SimpleTrigger getObject() {
 		return this.simpleTrigger;
 	}

spring-context-support/src/main/java/org/springframework/ui/freemarker/FreeMarkerConfigurationFactoryBean.java

@@ -65,6 +65,7 @@ public class FreeMarkerConfigurationFactoryBean extends FreeMarkerConfigurationF
 
 
 	@Override
+	@Nullable
 	public Configuration getObject() {
 		return this.configuration;
 	}