feat(client): implement listRelations

src/main/java/dev/openfga/sdk/api/client/ClientBatchCheckResponse.java

@@ -14,7 +14,6 @@
 
 import dev.openfga.sdk.api.model.CheckResponse;
 import dev.openfga.sdk.errors.FgaError;
-
 import java.util.List;
 import java.util.Map;
 import java.util.function.BiFunction;

src/main/java/dev/openfga/sdk/api/client/ClientListRelationsResponse.java

@@ -0,0 +1,23 @@
+package dev.openfga.sdk.api.client;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class ClientListRelationsResponse {
+    private final List<String> relations;
+
+    public ClientListRelationsResponse(List<String> relations) {
+        this.relations = relations;
+    }
+
+    public List<String> getRelations() {
+        return relations;
+    }
+
+    public static ClientListRelationsResponse fromBatchCheckResponses(List<ClientBatchCheckResponse> responses) {
+        return new ClientListRelationsResponse(responses.stream()
+                .filter(ClientBatchCheckResponse::getAllowed)
+                .map(batchCheckResponse -> batchCheckResponse.getRequest().getRelation())
+                .collect(Collectors.toList()));
+    }
+}

src/main/java/dev/openfga/sdk/api/client/OpenFgaClient.java

@@ -22,6 +22,7 @@
 import java.util.List;
 import java.util.concurrent.*;
 import java.util.function.Consumer;
+import java.util.stream.Collectors;
 
 public class OpenFgaClient {
     private final ApiClient apiClient;
@@ -491,9 +492,24 @@ public CompletableFuture<ClientListObjectsResponse> listObjects(
     }
 
     /*
-     * ListRelations - List all the relations a user has with an object (evaluates)
+     * ListRelations - List allowed relations a user has with an object (evaluates)
      */
-    // TODO
+    public CompletableFuture<ClientListRelationsResponse> listRelations(
+            ClientListRelationsRequest request, ClientBatchCheckOptions options) throws FgaInvalidParameterException {
+        if (request.getRelations().isEmpty()) {
+            throw new FgaInvalidParameterException(
+                    "At least 1 relation to check has to be provided when calling ListRelations");
+        }
+
+        var batchCheckRequests = request.getRelations().stream()
+                .map(relation -> new ClientCheckRequest()
+                        .user(request.getUser())
+                        .relation(relation)
+                        ._object(request.getObject()))
+                .collect(Collectors.toList());
+
+        return batchCheck(batchCheckRequests, options).thenApply(ClientListRelationsResponse::fromBatchCheckResponses);
+    }
 
     /* ************
      * Assertions *

src/main/java/dev/openfga/sdk/errors/FgaInvalidParameterException.java

@@ -1,6 +1,10 @@
 package dev.openfga.sdk.errors;
 
 public class FgaInvalidParameterException extends Exception {
+    public FgaInvalidParameterException(String message) {
+        super(message);
+    }
+
     public FgaInvalidParameterException(String paramName, String functionName) {
         super(message(paramName, functionName));
     }