remove wildcard imports, add helper method

Author: Maciej Mierzwa

src/main/java/org/opensearch/security/securityconf/DynamicConfigModelV7.java

@@ -182,7 +182,14 @@ public List<ClientBlockRegistry<InetAddress>> getIpClientBlockRegistries() {
     public Multimap<String, ClientBlockRegistry<String>> getAuthBackendClientBlockRegistries() {
         return Multimaps.unmodifiableMultimap(authBackendClientBlockRegistries);
     }
-    
+
+    public String getExtensionsSigningKey() {
+        return config.dynamic.extensions.getSigningKey();
+    }
+
+    public String getExtensionsEncryptionKey() {
+        return config.dynamic.extensions.getEncryptionKey();
+    }
 
     private void buildAAA() {
 

src/main/java/org/opensearch/security/securityconf/impl/v7/ConfigV7.java

@@ -33,7 +33,11 @@
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
-import com.fasterxml.jackson.annotation.*;
+import com.fasterxml.jackson.annotation.JsonAnyGetter;
+import com.fasterxml.jackson.annotation.JsonAnySetter;
+import com.fasterxml.jackson.annotation.JsonIgnore;
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.core.JsonProcessingException;
 
 import org.opensearch.security.DefaultObjectMapper;