Revisit nullability annotations

This commit introduces the following changes.

1) It adds a new Spring @NonNull annotation which allows to apply
@NonNullApi semantic on a specific element, like @Nullable does.
Combined with @Nullable, it allows partial null-safety support when
package granularity is too broad.

2) @Nullable and @NonNull can apply to ElementType.TYPE_USE in order
to be used on generic type arguments (SPR-15942).

3) Annotations does not apply to ElementType.TYPE_PARAMETER anymore
since it is not supported yet (applicability for such use case is
controversial and need to be discussed).

4) @NonNullApi does not apply to ElementType.FIELD anymore since in a
lot of use cases (private, protected) it is not part for the public API
+ its usage should remain opt-in. A dedicated @NonNullFields annotation
has been added in order to set fields default to non-nullable.

5) Updated Javadoc and reference documentation.

Issue: SPR-15756

spring-jms/src/main/java/org/springframework/jms/annotation/package-info.java

@@ -2,6 +2,8 @@
  * Annotations and support classes for declarative JMS listener endpoints.
  */
 @NonNullApi
+@NonNullFields
 package org.springframework.jms.annotation;
 
 import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-jms/src/main/java/org/springframework/jms/config/package-info.java

@@ -3,6 +3,8 @@
  * with Java configuration and XML schema support.
  */
 @NonNullApi
+@NonNullFields
 package org.springframework.jms.config;
 
 import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-jms/src/main/java/org/springframework/jms/connection/package-info.java

@@ -3,6 +3,8 @@
  * JMS ConnectionFactory, and a SingleConnectionFactory adapter.
  */
 @NonNullApi
+@NonNullFields
 package org.springframework.jms.connection;
 
 import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-jms/src/main/java/org/springframework/jms/core/package-info.java

@@ -3,6 +3,8 @@
  * Provides a JmsTemplate class and various callback interfaces.
  */
 @NonNullApi
+@NonNullFields
 package org.springframework.jms.core;
 
 import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-jms/src/main/java/org/springframework/jms/core/support/package-info.java

@@ -3,6 +3,8 @@
  * Contains a base class for JmsTemplate usage.
  */
 @NonNullApi
+@NonNullFields
 package org.springframework.jms.core.support;
 
 import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-jms/src/main/java/org/springframework/jms/listener/adapter/package-info.java

@@ -4,6 +4,8 @@
  * (such as String or byte array) that get passed into listener methods.
  */
 @NonNullApi
+@NonNullFields
 package org.springframework.jms.listener.adapter;
 
 import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-jms/src/main/java/org/springframework/jms/listener/endpoint/package-info.java

@@ -2,6 +2,8 @@
  * This package provides JCA-based endpoint management for JMS message listeners.
  */
 @NonNullApi
+@NonNullFields
 package org.springframework.jms.listener.endpoint;
 
 import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-jms/src/main/java/org/springframework/jms/listener/package-info.java

@@ -4,6 +4,8 @@
  * implementations, based on the plain JMS client API.
  */
 @NonNullApi
+@NonNullFields
 package org.springframework.jms.listener;
 
 import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-jms/src/main/java/org/springframework/jms/package-info.java

@@ -3,6 +3,8 @@
  * allowing for Spring-style JMS access.
  */
 @NonNullApi
+@NonNullFields
 package org.springframework.jms;
 
 import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-jms/src/main/java/org/springframework/jms/remoting/package-info.java

@@ -6,6 +6,8 @@
  * service: They only need to agree on a queue name and a service interface.
  */
 @NonNullApi
+@NonNullFields
 package org.springframework.jms.remoting;
 
 import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-jms/src/main/java/org/springframework/jms/support/converter/package-info.java

@@ -3,6 +3,8 @@
  * between Java objects and JMS messages.
  */
 @NonNullApi
+@NonNullFields
 package org.springframework.jms.support.converter;
 
 import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-jms/src/main/java/org/springframework/jms/support/destination/package-info.java

@@ -2,6 +2,8 @@
  * Support classes for Spring's JMS framework.
  */
 @NonNullApi
+@NonNullFields
 package org.springframework.jms.support.destination;
 
 import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-jms/src/main/java/org/springframework/jms/support/package-info.java

@@ -3,6 +3,8 @@
  * to be used by higher-level classes like JmsTemplate.
  */
 @NonNullApi
+@NonNullFields
 package org.springframework.jms.support;
 
 import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;