Ignore proxies when scanning for field resolvers.

src/main/kotlin/com/coxautodev/graphql/tools/FieldResolverScanner.kt

@@ -9,6 +9,7 @@ import org.apache.commons.lang3.reflect.FieldUtils
 import org.slf4j.LoggerFactory
 import java.lang.reflect.Modifier
 import java.lang.reflect.ParameterizedType
+import java.lang.reflect.Proxy
 import java.lang.reflect.Type
 import kotlin.reflect.full.valueParameters
 import kotlin.reflect.jvm.javaType
@@ -25,7 +26,7 @@ internal class FieldResolverScanner(val options: SchemaParserOptions) {
         private val log = LoggerFactory.getLogger(FieldResolverScanner::class.java)
 
         fun getAllMethods(type: JavaType) =
-                (type.unwrap().declaredMethods.toList()
+                (type.unwrap().declaredNonProxyMethods.toList()
                         + ClassUtils.getAllInterfaces(type.unwrap()).flatMap { it.methods.toList() }
                         + ClassUtils.getAllSuperclasses(type.unwrap()).flatMap { it.methods.toList() })
                         .asSequence()

src/main/kotlin/com/coxautodev/graphql/tools/Utils.kt

@@ -8,6 +8,7 @@ import graphql.language.ObjectTypeExtensionDefinition
 import graphql.language.Type
 import java.lang.reflect.Method
 import java.lang.reflect.ParameterizedType
+import java.lang.reflect.Proxy
 
 /**
  * @author Andrew Potter
@@ -16,6 +17,7 @@ import java.lang.reflect.ParameterizedType
 internal typealias GraphQLRootResolver = GraphQLResolver<Void>
 
 internal typealias JavaType = java.lang.reflect.Type
+internal typealias JavaMethod = java.lang.reflect.Method
 internal typealias GraphQLLangType = graphql.language.Type<*>
 
 internal fun Type<*>.unwrap(): Type<*> = when (this) {
@@ -35,6 +37,15 @@ internal fun JavaType.unwrap(): Class<out Any> =
             this as Class<*>
         }
 
+
+internal val Class<*>.declaredNonProxyMethods: List<JavaMethod>
+    get() {
+        return when {
+            Proxy.isProxyClass(this) -> emptyList()
+            else -> this.declaredMethods.toList()
+        }
+    }
+
 /**
  * Simple heuristic to check is a method is a trivial data fetcher.
  *
@@ -51,4 +62,5 @@ internal fun isTrivialDataFetcher(method: Method): Boolean {
 
 private fun isBooleanGetter(method: Method) = (method.name.startsWith("is")
         && (method.returnType == java.lang.Boolean::class.java)
-        || method.returnType == Boolean::class.java)
+        || method.returnType == Boolean::class.java)
+

src/test/kotlin/com/coxautodev/graphql/tools/MethodFieldResolverTest.kt

@@ -7,11 +7,15 @@ import graphql.schema.Coercing
 import graphql.schema.GraphQLScalarType
 import org.junit.Assert
 import org.junit.Test
+import java.lang.reflect.InvocationHandler
+import java.lang.reflect.Method
+import java.lang.reflect.Proxy
+import java.util.*
 
 class MethodFieldResolverTest {
 
     @Test
-    fun `should handle scalar types as method input argument`() {
+    fun shouldHandleScalarTypesAsMethodInputArgument() {
         val schema = SchemaParser.newParser()
                 .schemaString("""
                     scalar CustomScalar
@@ -44,7 +48,7 @@ class MethodFieldResolverTest {
     }
 
     @Test
-    fun `should handle lists of scalar types`() {
+    fun shouldHandleListsOfScalarTypes() {
         val schema = SchemaParser.newParser()
                 .schemaString("""
                     scalar CustomScalar
@@ -76,6 +80,55 @@ class MethodFieldResolverTest {
         Assert.assertEquals(6, result.getData<Map<String, Any>>()["test"])
     }
 
+    @Test
+    fun shouldHandleProxies() {
+        val invocationHandler = object : InvocationHandler {
+            override fun invoke(proxy: Any, method: Method, args: Array<out Any>): Any {
+                return when (method.name) {
+                    "toString" -> "Proxy$" + System.identityHashCode(this)
+                    "hashCode" -> System.identityHashCode(this)
+                    "equals" -> Proxy.isProxyClass(args[0].javaClass)
+                    "test" -> (args[0] as List<*>).map { (it as CustomScalar).value.length }.sum()
+                    else -> UnsupportedOperationException()
+                }
+            }
+        }
+
+        val resolver = Proxy.newProxyInstance(
+                MethodFieldResolverTest::class.java.classLoader,
+                arrayOf(Resolver::class.java, GraphQLQueryResolver::class.java),
+                invocationHandler
+        )  as GraphQLQueryResolver
+
+        val schema = SchemaParser.newParser()
+                .schemaString("""
+                    scalar CustomScalar
+                    type Query {
+                        test(input: [CustomScalar]): Int
+                    }
+                    """.trimIndent()
+                )
+                .scalars(customScalarType)
+                .resolvers(resolver)
+                .build()
+                .makeExecutableSchema()
+
+        val gql = GraphQL.newGraphQL(schema).build()
+
+        val result = gql
+                .execute(ExecutionInput.newExecutionInput()
+                        .query("""
+                            query Test(${"$"}input: [CustomScalar]) {
+                                test(input: ${"$"}input)
+                            }
+                            """.trimIndent())
+                        .variables(mapOf("input" to listOf("Foo", "Bar")))
+                        .context(Object())
+                        .root(Object()))
+
+        Assert.assertEquals(6, result.getData<Map<String, Any>>()["test"])
+    }
+
     /**
      * Custom Scalar Class type that doesn't work with Jackson serialization/deserialization
      */
@@ -90,6 +143,10 @@ class MethodFieldResolverTest {
         }
     }
 
+    interface Resolver {
+        fun test(scalars: List<CustomScalar>): Int
+    }
+
     private val customScalarType: GraphQLScalarType = GraphQLScalarType.newScalar()
             .name("CustomScalar")
             .description("customScalar")