GUACAMOLE-1218: Use static instances of Logger per established coding practices.

extensions/guacamole-auth-json/src/main/java/org/apache/guacamole/auth/json/RequestValidationService.java

@@ -36,7 +36,7 @@ public class RequestValidationService {
     /**
      * Logger for this class.
      */
-    private final Logger logger = LoggerFactory.getLogger(RequestValidationService.class);
+    private static final Logger logger = LoggerFactory.getLogger(RequestValidationService.class);
 
     /**
      * Service for retrieving configuration information regarding the

extensions/guacamole-auth-json/src/main/java/org/apache/guacamole/auth/json/connection/ConnectionService.java

@@ -56,7 +56,7 @@ public class ConnectionService {
     /**
      * Logger for this class.
      */
-    private final Logger logger = LoggerFactory.getLogger(ConnectionService.class);
+    private static final Logger logger = LoggerFactory.getLogger(ConnectionService.class);
 
     /**
      * The Guacamole server environment.

extensions/guacamole-auth-json/src/main/java/org/apache/guacamole/auth/json/user/UserDataDenylist.java

@@ -38,7 +38,7 @@ public class UserDataDenylist {
     /**
      * Logger for this class.
      */
-    private final Logger logger = LoggerFactory.getLogger(UserDataDenylist.class);
+    private static final Logger logger = LoggerFactory.getLogger(UserDataDenylist.class);
 
     /**
      * All denylisted UserData objects, stored by their associated

extensions/guacamole-auth-json/src/main/java/org/apache/guacamole/auth/json/user/UserDataService.java

@@ -56,7 +56,7 @@ public class UserDataService {
     /**
      * Logger for this class.
      */
-    private final Logger logger = LoggerFactory.getLogger(UserDataService.class);
+    private static final Logger logger = LoggerFactory.getLogger(UserDataService.class);
 
     /**
      * ObjectMapper for deserializing UserData objects.