minor fixes:

fixed method naming
added dirtiesContext annotation to classes that shouldnt share the app context state
using SpringApplication instead of unnecessary SpringApplicationBuilder

spring-protobuf/src/test/java/com/baeldung/protobuf/ApplicationIntegrationTest.java

@@ -16,12 +16,14 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
 import org.springframework.http.ResponseEntity;
+import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
 import org.springframework.web.client.RestTemplate;
 
 import com.baeldung.protobuf.BaeldungTraining.Course;
 import com.googlecode.protobuf.format.JsonFormat;
 
+@DirtiesContext
 @RunWith(SpringJUnit4ClassRunner.class)
 @SpringBootTest(classes = Application.class, webEnvironment = WebEnvironment.DEFINED_PORT)
 public class ApplicationIntegrationTest {

spring-protobuf/src/test/java/org/baeldung/SpringContextIntegrationTest.java

@@ -3,10 +3,12 @@ package org.baeldung;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.junit4.SpringRunner;
 
 import com.baeldung.protobuf.Application;
 
+@DirtiesContext
 @RunWith(SpringRunner.class)
 @SpringBootTest(classes = Application.class)
 public class SpringContextIntegrationTest {