Avoid double-parenthesis in JpqlQueryBuilder.InPredicate rendering

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/JpqlQueryBuilder.java

@@ -44,6 +44,7 @@
  * A Domain-Specific Language to build JPQL queries using Java code.
  *
  * @author Mark Paluch
+ * @author Choi Wang Gyu
  */
 @SuppressWarnings("JavadocDeclaration")
 public final class JpqlQueryBuilder {
@@ -1422,8 +1423,14 @@ record InPredicate(Expression path, String operator, Expression predicate) imple
 		@Override
 		public String render(RenderContext context) {
 
-			// TODO: should we rather wrap it with nested or check if its a nested predicate before we call render
-			return "%s %s (%s)".formatted(path.render(context), operator, predicate.render(context));
+			String predicateStr = predicate.render(context);
+
+			// Avoid double parentheses if predicate string already starts and ends with parentheses
+			if (predicateStr.startsWith("(") && predicateStr.endsWith(")")) {
+				return "%s %s %s".formatted(path.render(context), operator, predicateStr);
+			}
+
+			return "%s %s (%s)".formatted(path.render(context), operator, predicateStr);
 		}
 
 		@Override

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/query/JpqlQueryBuilderUnitTests.java

@@ -34,6 +34,7 @@
  *
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author Choi Wang Gyu
  */
 class JpqlQueryBuilderUnitTests {
 
@@ -136,6 +137,31 @@ void predicateRendering() {
 		assertThat(where.neq(expression("'AT'")).render(context)).isEqualTo("o.country != 'AT'");
 	}
 
+	@Test // GH-3961 - Nested predicate parentheses handling
+	void inPredicateWithNestedExpression() {
+
+		Entity entity = JpqlQueryBuilder.entity(Order.class);
+		WhereStep where = JpqlQueryBuilder.where(JpqlQueryBuilder.path(entity, "country"));
+		RenderContext context = ctx(entity);
+
+		// Test regular IN predicate with parentheses
+		assertThat(where.in(expression("'AT', 'DE'")).render(context)).isEqualTo("o.country IN ('AT', 'DE')");
+
+		// Test IN predicate with already parenthesized expression - should avoid double parentheses
+		Expression parenthesizedExpression = expression("('AT', 'DE')");
+		assertThat(where.in(parenthesizedExpression).render(context))
+				.isEqualTo("o.country IN ('AT', 'DE')");
+
+		// Test NOT IN predicate with already parenthesized expression
+		assertThat(where.notIn(parenthesizedExpression).render(context))
+				.isEqualTo("o.country NOT IN ('AT', 'DE')");
+
+		// Test IN with subquery (already parenthesized)
+		Expression subqueryExpression = expression("(SELECT c.code FROM Country c WHERE c.active = true)");
+		assertThat(where.in(subqueryExpression).render(context))
+				.isEqualTo("o.country IN (SELECT c.code FROM Country c WHERE c.active = true)");
+	}
+
 	@Test // GH-3588
 	void selectRendering() {