Add maven compiler plugin for java 11

core-java-modules/core-java-exceptions-3/pom.xml

@@ -26,6 +26,19 @@
         </dependency>
     </dependencies>
 
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>11</source>
+                    <target>11</target>
+                    <compilerVersion>11</compilerVersion>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
     <properties>
         <!-- testing -->
         <assertj-core.version>3.10.0</assertj-core.version>