Remove spring dependencies from internal code (#3937)

* add tech-support-qq-4.png

* Update README.md

* Enhance the user experience in the scenario of submitting duplicate keys

* Modify the key-value conflict exception prompt, adjust the code style

* fix:Remove spring dependencies from internal code

* doc(CHANGES.md): update CHANGES.md

Co-authored-by: Jason Song <nobodyiam@gmail.com>

CHANGES.md

@@ -11,6 +11,7 @@ Apollo 1.10.0
 * [switch apollo.config-service log from warning to info level](https://github.com/ctripcorp/apollo/pull/3884)
 * [Make Access Key Timestamp check configurable](https://github.com/ctripcorp/apollo/pull/3908)
 * [remove ctrip profile](https://github.com/ctripcorp/apollo/pull/3920)
+* [Remove spring dependencies from internal code](https://github.com/apolloconfig/apollo/pull/3937)
 
 ------------------
 All issues and pull requests are [here](https://github.com/ctripcorp/apollo/milestone/8?closed=1)

apollo-client/src/main/java/com/ctrip/framework/apollo/internals/DefaultConfig.java

@@ -39,8 +39,6 @@
 import com.ctrip.framework.apollo.util.ExceptionUtil;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.util.concurrent.RateLimiter;
-import org.springframework.util.CollectionUtils;
-
 
 /**
  * @author Jason Song(song_s@ctrip.com)
@@ -186,10 +184,10 @@ public Set<String> getPropertyNames() {
     // propertyNames include system property and system env might cause some compatibility issues, though that looks like the correct implementation.
     Set<String> fromRepository = this.getPropertyNamesFromRepository();
     Set<String> fromAdditional = this.getPropertyNamesFromAdditional();
-    if (CollectionUtils.isEmpty(fromRepository)) {
+    if (fromRepository == null || fromRepository.isEmpty()) {
       return fromAdditional;
     }
-    if (CollectionUtils.isEmpty(fromAdditional)) {
+    if (fromAdditional == null || fromAdditional.isEmpty()) {
       return fromRepository;
     }
     Set<String> propertyNames = Sets