do not take methods of inherited interface which is not marked as service contract.

this will reflect the GRPC behavior which such interface's methods.

Author: Meir Kriheli

src/protobuf-net.Grpc.Reflection/SchemaGenerator.cs

@@ -49,7 +49,7 @@ public string GetSchema(Type contractType)
                 Name = name
             };
 
-            var ops = GetMethodsRecursively(contractType);
+            var ops = GetMethodsRecursively(binder, contractType);
             foreach (var method in ops)
             {
                 if (method.DeclaringType == typeof(object))
@@ -103,11 +103,14 @@ static Type ApplySubstitutes(Type type)
             }
         }
 
-        private static MethodInfo[] GetMethodsRecursively(Type contractType)
+        private static MethodInfo[] GetMethodsRecursively(ServiceBinder serviceBinder, Type contractType)
         {
             var methods = contractType.GetMethods(BindingFlags.Public | BindingFlags.Instance);
-            var baseInterfaces = contractType.GetInterfaces();
-            var inheritedMethods = baseInterfaces.SelectMany(iface => GetMethodsRecursively(iface)).ToArray();
+            var baseContractInterfaces = 
+                contractType.GetInterfaces()
+                .Where(cType => serviceBinder.IsServiceContract(cType, out _)); // only the ones marked as contract type 
+
+            var inheritedMethods = baseContractInterfaces.SelectMany(cType => GetMethodsRecursively(serviceBinder, cType)).ToArray();
             if (inheritedMethods.Any())
                 return inheritedMethods.Concat(methods).ToArray();
 

tests/protobuf-net.Grpc.Reflection.Test/SchemaGeneration.cs

@@ -110,14 +110,29 @@ public interface IMyService
             void SyncEmpty();
         }
 
+        /// <summary>
+        /// An interface which is not marked with [Service] attribute.
+        /// Its methods are not expected to participate in reflection at all.
+        /// </summary>
+        public interface INotAService
+        {
+            ValueTask<MyResponse> NotAServiceUnary(MyRequest request, CallContext callContext = default);
+            ValueTask<MyResponse> NotAServiceClientStreaming(IAsyncEnumerable<MyRequest> request, CallContext callContext = default);
+            IAsyncEnumerable<MyResponse> NotAServiceServerStreaming(MyRequest request, CallContext callContext = default);
+            IAsyncEnumerable<MyResponse> NotAServiceFullDuplex(IAsyncEnumerable<MyRequest> request, CallContext callContext = default);
+
+            ValueTask NotAServiceAsyncEmpty();
+            void NotAServiceSyncEmpty();
+        }
+
         [Service]
-        public interface ISomeGenericService<TGenericRequest, TGenericResult>
+        public interface ISomeGenericService<in TGenericRequest, TGenericResult>
         {
             ValueTask<TGenericResult> GenericUnary(TGenericRequest request, CallContext callContext = default);
         }
 
         [Service]
-        public interface IMyInheritedService : IMyService, ISomeGenericService<MyRequest, MyResponse>
+        public interface IMyInheritedService : IMyService, ISomeGenericService<MyRequest, MyResponse>, INotAService
         {
             ValueTask<MyResponse> InheritedUnary(MyRequest request, CallContext callContext = default);
             ValueTask<MyResponse> InheritedClientStreaming(IAsyncEnumerable<MyRequest> request, CallContext callContext = default);
@@ -212,5 +227,13 @@ service ConferencesService {
 }
 ", proto, ignoreLineEndingDifferences: true);
         }
+
+        [Fact]
+        public void WhenInterfaceIsNotServiceContract_Throw()
+        {
+            var generator = new SchemaGenerator();
+            Action activation = () => generator.GetSchema<INotAService>();
+            Assert.Throws<ArgumentException>(activation.Invoke);
+        }
     }
 }