Add a bean post processor for reactive stubs

Fixes gh-143

samples/grpc-reactive/src/main/java/org/springframework/grpc/sample/GrpcServerApplication.java

@@ -1,13 +1,35 @@
 package org.springframework.grpc.sample;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Import;
+import org.springframework.grpc.server.exception.GrpcExceptionHandler;
+import org.springframework.grpc.server.exception.ReactiveStubBeanDefinitionRegistrar;
+
+import io.grpc.Status;
 
 @SpringBootApplication
+@Import(ReactiveStubBeanDefinitionRegistrar.class)
 public class GrpcServerApplication {
 
+	private static Log log = LogFactory.getLog(GrpcServerApplication.class);
+
 	public static void main(String[] args) {
 		SpringApplication.run(GrpcServerApplication.class, args);
 	}
 
+	@Bean
+	GrpcExceptionHandler grpcExceptionHandler() {
+		return ex -> {
+			if (ex instanceof IllegalArgumentException) {
+				log.error("Error in grpc exception", ex);
+				return Status.INVALID_ARGUMENT.withDescription(ex.getMessage());
+			}
+			return Status.INTERNAL.withCause(ex).withDescription(ex.getMessage());
+		};
+	}
+
 }

samples/grpc-reactive/src/main/resources/application.properties

@@ -1 +1,2 @@
 spring.application.name=grpc-reactive
+#logging.level.org.springframework.beans.factory.support.CglibSubclassingInstantiationStrategy=TRACE