fixed a bug where in Spring Boot setting, AI Service method parameter is ignored without @V annotation

langchain4j/src/main/java/dev/langchain4j/service/DefaultAiServices.java

@@ -366,13 +366,10 @@ class DefaultAiServices<T> extends AiServices<T> {
 
         Map<String, Object> variables = new HashMap<>();
         for (int i = 0; i < parameters.length; i++) {
-            V annotation = parameters[i].getAnnotation(V.class);
-            if (annotation != null) {
-                String variableName = annotation.value();
+            String variableName = getVariableName(parameters[i]);
             Object variableValue = args[i];
             variables.put(variableName, variableValue);
         }
-        }
 
         if (template.contains("{{it}}") && !variables.containsKey("it")) {
             String itValue = getValueOfVariableIt(parameters, args);
@@ -382,6 +379,15 @@ class DefaultAiServices<T> extends AiServices<T> {
         return variables;
     }
 
+    private static String getVariableName(Parameter parameter) {
+        V annotation = parameter.getAnnotation(V.class);
+        if (annotation != null) {
+            return annotation.value();
+        } else {
+            return parameter.getName();
+        }
+    }
+
     private static String getValueOfVariableIt(Parameter[] parameters, Object[] args) {
         if (parameters.length == 1) {
             Parameter parameter = parameters[0];

langchain4j/src/main/java/dev/langchain4j/service/V.java

@@ -29,7 +29,7 @@ import static java.lang.annotation.RetentionPolicy.RUNTIME;
  * String chat(@V String name, @V int age);
  * </pre>
  * <p>
- * When using Spring Boot, defining the value of this annotation is not required.
+ * When using LangChain4j with Quarkus or Spring Boot, using this annotation is not necessary.
  *
  * @see UserMessage
  * @see SystemMessage

langchain4j/src/test/java/dev/langchain4j/service/AiServicesUserMessageConfigTest.java

@@ -47,6 +47,9 @@ class AiServicesUserMessageConfigTest {
         @UserMessage("What is the {{it}} of {{country}}?")
         String chat7(@V("it") String it, @V("country") String country);
 
+        @UserMessage("What is the capital of {{arg0}}?")
+        String chat8(String country);
+
         // illegal configuration
 
         String illegalChat1();
@@ -172,6 +175,21 @@ class AiServicesUserMessageConfigTest {
         verify(chatLanguageModel).supportedCapabilities();
     }
 
+    @Test
+    void test_user_message_configuration_8() {
+
+        // given
+        AiService aiService = AiServices.builder(AiService.class)
+                .chatLanguageModel(chatLanguageModel)
+                .build();
+
+        // when-then
+        assertThat(aiService.chat8("Germany"))
+                .containsIgnoringCase("Berlin");
+        verify(chatLanguageModel).generate(singletonList(userMessage("What is the capital of Germany?")));
+        verify(chatLanguageModel).supportedCapabilities();
+    }
+
     @Test
     void test_illegal_user_message_configuration_1() {