dont use non-blittable types in native method signatures
diff --git a/src/csharp/Grpc.Core/Internal/NativeMethods.cs b/src/csharp/Grpc.Core/Internal/NativeMethods.cs
index a98861a..696987d 100644
--- a/src/csharp/Grpc.Core/Internal/NativeMethods.cs
+++ b/src/csharp/Grpc.Core/Internal/NativeMethods.cs
@@ -346,11 +346,11 @@
             public delegate CallError grpcsharp_call_start_duplex_streaming_delegate(CallSafeHandle call,
                 BatchContextSafeHandle ctx, MetadataArraySafeHandle metadataArray, CallFlags metadataFlags);
             public delegate CallError grpcsharp_call_send_message_delegate(CallSafeHandle call,
-                BatchContextSafeHandle ctx, byte[] sendBuffer, UIntPtr sendBufferLen, WriteFlags writeFlags, bool sendEmptyInitialMetadata);
+                BatchContextSafeHandle ctx, byte[] sendBuffer, UIntPtr sendBufferLen, WriteFlags writeFlags, int sendEmptyInitialMetadata);
             public delegate CallError grpcsharp_call_send_close_from_client_delegate(CallSafeHandle call,
                 BatchContextSafeHandle ctx);
             public delegate CallError grpcsharp_call_send_status_from_server_delegate(CallSafeHandle call,
-                BatchContextSafeHandle ctx, StatusCode statusCode, byte[] statusMessage, UIntPtr statusMessageLen, MetadataArraySafeHandle metadataArray, bool sendEmptyInitialMetadata,
+                BatchContextSafeHandle ctx, StatusCode statusCode, byte[] statusMessage, UIntPtr statusMessageLen, MetadataArraySafeHandle metadataArray, int sendEmptyInitialMetadata,
                 byte[] optionalSendBuffer, UIntPtr optionalSendBufferLen, WriteFlags writeFlags);
             public delegate CallError grpcsharp_call_recv_message_delegate(CallSafeHandle call,
                 BatchContextSafeHandle ctx);
@@ -406,7 +406,7 @@
             public delegate CallCredentialsSafeHandle grpcsharp_metadata_credentials_create_from_plugin_delegate(NativeMetadataInterceptor interceptor);
             public delegate void grpcsharp_metadata_credentials_notify_from_plugin_delegate(IntPtr callbackPtr, IntPtr userData, MetadataArraySafeHandle metadataArray, StatusCode statusCode, string errorDetails);
 
-            public delegate ServerCredentialsSafeHandle grpcsharp_ssl_server_credentials_create_delegate(string pemRootCerts, string[] keyCertPairCertChainArray, string[] keyCertPairPrivateKeyArray, UIntPtr numKeyCertPairs, bool forceClientAuth);
+            public delegate ServerCredentialsSafeHandle grpcsharp_ssl_server_credentials_create_delegate(string pemRootCerts, string[] keyCertPairCertChainArray, string[] keyCertPairPrivateKeyArray, UIntPtr numKeyCertPairs, int forceClientAuth);
             public delegate void grpcsharp_server_credentials_release_delegate(IntPtr credentials);
 
             public delegate ServerSafeHandle grpcsharp_server_create_delegate(ChannelArgsSafeHandle args);