From 97fb6459e586f0078559ece512ed682b2be3395c Mon Sep 17 00:00:00 2001
From: Andreas Marek <andimarek@fastmail.fm>
Date: Tue, 19 May 2026 10:06:30 +1000
Subject: [PATCH] Fix input cycle validation for non-null lists

---
 .../validation/NoUnbrokenInputCycles.java     | 15 ++----
 .../NoUnbrokenInputCyclesTest.groovy          | 50 +++++++++++++++++++
 2 files changed, 54 insertions(+), 11 deletions(-)

diff --git a/src/main/java/graphql/schema/validation/NoUnbrokenInputCycles.java b/src/main/java/graphql/schema/validation/NoUnbrokenInputCycles.java
index 22be3f7148..9eb061d070 100644
--- a/src/main/java/graphql/schema/validation/NoUnbrokenInputCycles.java
+++ b/src/main/java/graphql/schema/validation/NoUnbrokenInputCycles.java
@@ -6,7 +6,6 @@
 import graphql.schema.GraphQLInputObjectField;
 import graphql.schema.GraphQLInputObjectType;
 import graphql.schema.GraphQLInputType;
-import graphql.schema.GraphQLList;
 import graphql.schema.GraphQLNonNull;
 import graphql.schema.GraphQLSchemaElement;
 import graphql.schema.GraphQLType;
@@ -63,17 +62,11 @@ private void check(GraphQLInputObjectType type, Set<GraphQLType> seen, List<Stri
     }
 
     private GraphQLType unwrapNonNull(GraphQLNonNull type) {
-        if (isList(type.getWrappedType())) {
-            //we only care about [type!]! i.e. non-null lists of non-nulls
-            GraphQLList listType = (GraphQLList) type.getWrappedType();
-            if (isNonNull(listType.getWrappedType())) {
-                return unwrapAll(listType.getWrappedType());
-            } else {
-                return type.getWrappedType();
-            }
-        } else {
-            return unwrapAll(type.getWrappedType());
+        GraphQLType wrappedType = type.getWrappedType();
+        if (isList(wrappedType)) {
+            return wrappedType;
         }
+        return unwrapAll(wrappedType);
     }
 
     private String getErrorMessage(List<String> path) {
diff --git a/src/test/groovy/graphql/schema/validation/NoUnbrokenInputCyclesTest.groovy b/src/test/groovy/graphql/schema/validation/NoUnbrokenInputCyclesTest.groovy
index 2ead346116..a9f0889e3d 100644
--- a/src/test/groovy/graphql/schema/validation/NoUnbrokenInputCyclesTest.groovy
+++ b/src/test/groovy/graphql/schema/validation/NoUnbrokenInputCyclesTest.groovy
@@ -1,9 +1,12 @@
 package graphql.schema.validation
 
+import graphql.TestUtil
 import graphql.schema.GraphQLArgument
 import graphql.schema.GraphQLFieldDefinition
 import graphql.schema.GraphQLInputObjectField
 import graphql.schema.GraphQLInputObjectType
+import graphql.schema.idl.SchemaGenerator
+import graphql.schema.idl.SchemaParser
 import graphql.util.TraverserContext
 import spock.lang.Specification
 
@@ -43,4 +46,51 @@ class NoUnbrokenInputCyclesTest extends Specification {
         then:
         errorCollector.containsValidationError(SchemaValidationErrorType.UnbrokenInputCycle)
     }
+
+    def "input object cycles through a non-null list are allowed"() {
+        def sdl = """
+            input Example {
+                self: [Example!]!
+                value: String
+            }
+
+            type Query {
+                example(example: Example): String
+            }
+        """
+
+        when:
+        def registry = new SchemaParser().parse(sdl)
+        new SchemaGenerator().makeExecutableSchema(registry, TestUtil.getMockRuntimeWiring())
+
+        then:
+        noExceptionThrown()
+    }
+
+    def "longer input object cycles through a non-null list are allowed"() {
+        def sdl = """
+            input Foo {
+                bar: Bar!
+            }
+
+            input Bar {
+                baz: Baz!
+            }
+
+            input Baz {
+                foos: [Foo!]!
+            }
+
+            type Query {
+                foo(foo: Foo): String
+            }
+        """
+
+        when:
+        def registry = new SchemaParser().parse(sdl)
+        new SchemaGenerator().makeExecutableSchema(registry, TestUtil.getMockRuntimeWiring())
+
+        then:
+        noExceptionThrown()
+    }
 }