Fixed most reported issues by SonarCloud.

partial-response/pom.xml

@@ -44,6 +44,11 @@
             <artifactId>junit-vintage-engine</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.mockito</groupId>
             <artifactId>mockito-core</artifactId>

partial-response/src/test/java/com/iluwatar/partialresponse/AppTest.java

@@ -25,14 +25,16 @@ package com.iluwatar.partialresponse;
 
 import org.junit.Test;
 
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
 /**
  * Application test
  */
 public class AppTest {
 
   @Test
-  public void main() throws Exception {
-    App.main(new String[]{});
+  public void shouldExecuteApplicationWithoutException() {
+    assertDoesNotThrow(() -> App.main(new String[]{}));
   }
 
 }