GUACAMOLE-641: Migrate existing extensions to singleton LocalEnvironment.

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

@@ -59,7 +59,7 @@ public class JSONAuthenticationProviderModule extends AbstractModule {
             throws GuacamoleException {
 
         // Get local environment
-        this.environment = new LocalEnvironment();
+        this.environment = LocalEnvironment.getInstance();
 
         // Store associated auth provider
         this.authProvider = authProvider;