Do not fail on setAccessible

src/main/kotlin/graphql/kickstart/tools/resolver/FieldResolverScanner.kt

@@ -12,6 +12,7 @@ import graphql.schema.DataFetchingEnvironment
 import org.apache.commons.lang3.ClassUtils
 import org.apache.commons.lang3.reflect.FieldUtils
 import org.slf4j.LoggerFactory
+import java.lang.reflect.AccessibleObject
 import java.lang.reflect.Method
 import java.lang.reflect.Modifier
 import java.lang.reflect.Type
@@ -44,13 +45,13 @@ internal class FieldResolverScanner(val options: SchemaParserOptions) {
     private fun findFieldResolver(field: FieldDefinition, search: Search, scanProperties: Boolean): FieldResolver? {
         val method = findResolverMethod(field, search)
         if (method != null) {
-            return MethodFieldResolver(field, search, options, method.apply { isAccessible = true })
+            return MethodFieldResolver(field, search, options, method.apply(trySetAccessible(field, search.type)))
         }
 
         if (scanProperties) {
             val property = findResolverProperty(field, search)
             if (property != null) {
-                return PropertyFieldResolver(field, search, options, property.apply { isAccessible = true })
+                return PropertyFieldResolver(field, search, options, property.apply(trySetAccessible(field, search.type)))
             }
         }
 
@@ -61,6 +62,15 @@ internal class FieldResolverScanner(val options: SchemaParserOptions) {
         return null
     }
 
+    private fun trySetAccessible(field: FieldDefinition, type: JavaType): AccessibleObject.() -> Unit = {
+        try {
+            isAccessible = true
+        } catch (e: RuntimeException) {
+            log.warn("Unable to make field ${type.unwrap().name}#${field.name} accessible. " +
+                "Be sure to provide a resolver or open the enclosing module if possible.")
+        }
+    }
+
     private fun missingFieldResolver(field: FieldDefinition, searches: List<Search>, scanProperties: Boolean): FieldResolver {
         return if (options.allowUnimplementedResolvers || options.missingResolverDataFetcher != null) {
             if (options.allowUnimplementedResolvers) {

src/test/kotlin/graphql/kickstart/tools/InaccessibleFieldResolverTest.kt

@@ -0,0 +1,98 @@
+package graphql.kickstart.tools
+
+import graphql.ExceptionWhileDataFetching
+import graphql.GraphQL
+import graphql.execution.AsyncExecutionStrategy
+import graphql.schema.GraphQLSchema
+import org.junit.Ignore
+import org.junit.Test
+import java.util.*
+
+/**
+ * Reflective access to private fields in closed modules is not possible since Java 17.
+ * When using objects from closed modules in the schema the field resolver scanner will try to access their fields but fail.
+ * If no other resolver is provided that will result in an [IllegalAccessException]
+ */
+class InaccessibleFieldResolverTest {
+
+    @Test
+    @Ignore // TODO enable test after upgrading to 17
+    fun `private field from closed module is not accessible`() {
+        val schema: GraphQLSchema = SchemaParser.newParser()
+            .schemaString(
+                """
+                type Query {
+                    locale: Locale
+                }
+
+                type Locale {
+                  country: String!
+                  languageTag: String!
+                }
+                """)
+            .resolvers(Query())
+            .build()
+            .makeExecutableSchema()
+        val gql: GraphQL = GraphQL.newGraphQL(schema)
+            .queryExecutionStrategy(AsyncExecutionStrategy())
+            .build()
+
+        val result = gql.execute(
+            """
+            query {
+                locale {
+                    country
+                    languageTag
+                }
+            }
+            """
+        )
+
+        assertEquals(result.errors.size, 1)
+        val exceptionWhileDataFetching = result.errors[0] as ExceptionWhileDataFetching
+        assert(exceptionWhileDataFetching.exception is IllegalAccessException)
+    }
+
+    @Test
+    fun `private field from closed module is accessible through resolver`() {
+        val schema: GraphQLSchema = SchemaParser.newParser()
+            .schemaString(
+                """
+                type Query {
+                    locale: Locale
+                }
+
+                type Locale {
+                  country: String!
+                  languageTag: String!
+                }
+                """)
+            .resolvers(Query(), LocaleResolver())
+            .build()
+            .makeExecutableSchema()
+        val gql: GraphQL = GraphQL.newGraphQL(schema)
+            .queryExecutionStrategy(AsyncExecutionStrategy())
+            .build()
+
+        val data = assertNoGraphQlErrors(gql) {
+            """
+            query {
+                locale {
+                    country
+                    languageTag
+                }
+            }
+            """
+        }
+
+        assertEquals(data["locale"], mapOf("country" to "US", "languageTag" to "en-US"))
+    }
+
+    class Query : GraphQLQueryResolver {
+        fun locale(): Locale = Locale.US
+    }
+
+    class LocaleResolver : GraphQLResolver<Locale> {
+        fun languageTag(locale: Locale): String = locale.toLanguageTag()
+    }
+}