Wrap underlying checked exception with IllegalStateException. Add tests.

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/FeignCircuitBreakerInvocationHandler.java

@@ -113,6 +113,9 @@ class FeignCircuitBreakerInvocationHandler implements InvocationHandler {
 			if (underlyingException instanceof RuntimeException) {
 				throw (RuntimeException) underlyingException;
 			}
+			if (underlyingException != null) {
+				throw new IllegalStateException(underlyingException);
+			}
 			throw new IllegalStateException(exception);
 		}
 	}

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/circuitbreaker/CircuitBreakerTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.cloud.openfeign.circuitbreaker;
 
+import java.io.IOException;
 import java.util.function.Function;
 
 import org.apache.commons.logging.Log;
@@ -49,6 +50,7 @@ import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RestController;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 
 /**
  * @author Spencer Gibb
@@ -65,6 +67,9 @@ public class CircuitBreakerTests {
 	@Autowired
 	TestClient testClient;
 
+	@Autowired
+	ExceptionClient exceptionClient;
+
 	@Autowired
 	TestClientWithFactory testClientWithFactory;
 
@@ -111,6 +116,17 @@ public class CircuitBreakerTests {
 		assertThat(testClientWithFactory.getException()).isEqualTo("Fixed response");
 	}
 
+	@Test
+	void testRuntimeExceptionUnwrapped() {
+		assertThatExceptionOfType(UnsupportedOperationException.class)
+				.isThrownBy(() -> exceptionClient.getRuntimeException());
+	}
+
+	@Test
+	void testCheckedExceptionWrapped() {
+		assertThatExceptionOfType(IllegalStateException.class).isThrownBy(() -> exceptionClient.getCheckedException());
+	}
+
 	@FeignClient(name = "test", url = "http://localhost:${server.port}/", fallback = Fallback.class)
 	protected interface TestClient {
 
@@ -122,6 +138,18 @@ public class CircuitBreakerTests {
 
 	}
 
+	@FeignClient(name = "exceptionClient", url = "http://localhost:${server.port}/",
+			fallbackFactory = ExceptionThrowingFallbackFactory.class)
+	protected interface ExceptionClient {
+
+		@GetMapping("/runtimeException")
+		Hello getRuntimeException();
+
+		@GetMapping("/runtimeException")
+		Hello getCheckedException() throws IOException;
+
+	}
+
 	@Component
 	static class Fallback implements TestClient {
 
@@ -159,6 +187,25 @@ public class CircuitBreakerTests {
 
 	}
 
+	static class ExceptionThrowingFallbackFactory implements FallbackFactory<ExceptionClient> {
+
+		@Override
+		public ExceptionClient create(Throwable cause) {
+			return new ExceptionClient() {
+				@Override
+				public Hello getRuntimeException() {
+					throw new UnsupportedOperationException("Not implemented!");
+				}
+
+				@Override
+				public Hello getCheckedException() throws IOException {
+					throw new IOException();
+				}
+			};
+		}
+
+	}
+
 	static class FallbackWithFactory implements TestClientWithFactory {
 
 		@Override
@@ -176,7 +223,7 @@ public class CircuitBreakerTests {
 	@Configuration(proxyBeanMethods = false)
 	@EnableAutoConfiguration
 	@RestController
-	@EnableFeignClients(clients = { TestClient.class, TestClientWithFactory.class })
+	@EnableFeignClients(clients = { TestClient.class, TestClientWithFactory.class, ExceptionClient.class })
 	@Import(NoSecurityConfiguration.class)
 	protected static class Application implements TestClient {
 
@@ -228,6 +275,11 @@ public class CircuitBreakerTests {
 			return new TestFallbackFactory();
 		}
 
+		@Bean
+		ExceptionThrowingFallbackFactory exceptionThrowingFallbackFactory() {
+			return new ExceptionThrowingFallbackFactory();
+		}
+
 	}
 
 }