fix(rbac): drop permissions which the current version of the client does not know how to read

Author: bevzzz

src/main/java/io/weaviate/client6/v1/api/rbac/Permission.java

@@ -36,6 +36,7 @@ enum Kind implements JsonEnum<Kind> {
     GROUPS("groups"),
     ROLES("roles"),
     NODES("nodes"),
+    NAMESPACES("namespaces"),
     TENANTS("tenants"),
     REPLICATE("replicate"),
     USERS("users"),

src/main/java/io/weaviate/client6/v1/api/rbac/Role.java

@@ -3,6 +3,7 @@
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Objects;
 
 import com.google.gson.Gson;
 import com.google.gson.TypeAdapter;
@@ -43,6 +44,9 @@ public T read(JsonReader in) throws IOException {
           if (role.permissions == null) {
             return (T) role;
           }
+          // Permissions which are not known to this client version
+          // will be returned as null; we should drop them before merging.
+          role.permissions.removeIf(Objects::isNull);
           return (T) new Role(role.name(), Permission.merge(role.permissions));
         }
       };