@iluwatar compiling project with java 8 I don't get any other compiler warnings. Yes, I can confirm. We can close this issue.
Java 11 support: Get rid of compiler warnings
This task is part of the Java 11 transition plan https://github.com/iluwatar/java-design-patterns/wiki/16.-Java-11-Transition

In this task we run the regular build and inspect the compiler output for warnings. We are especially interested in deprecation warnings, those are going to break things when Java version is updated. The target of the task is to get rid of as many warnings as possible.
pom.xml trampoline/pom.xml
pom.xml trampoline/pom.xml
diff --git a/pom.xml b/pom.xml
index 5dfb1fff4376..eb3b68c498fb 100644
--- a/pom.xml
+++ b/pom.xml
@@ -38,7 +38,7 @@
         <junit-vintage.version>${junit.version}.2</junit-vintage.version>
         <junit-platform.version>1.0.2</junit-platform.version>
         <sping-test-junit5.version>1.0.2</sping-test-junit5.version>
-        <compiler.version>3.0</compiler.version>
+        <compiler.version>3.8.0</compiler.version>
         <jacoco.version>0.7.2.201409121644</jacoco.version>
         <commons-dbcp.version>1.4</commons-dbcp.version>
         <camel.version>2.16.1</camel.version>
@@ -357,15 +357,14 @@
         </pluginManagement>
 
         <plugins>
-            <!-- Tell maven to compile using Java 8 -->
+            <!-- Tell maven to compile using Java 11 -->
             <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-compiler-plugin</artifactId>
+			    <groupId>org.apache.maven.plugins</groupId>
+			    <artifactId>maven-compiler-plugin</artifactId>
                 <version>${compiler.version}</version>
-                <configuration>
-                    <source>1.8</source>
-                    <target>1.8</target>
-                </configuration>
+			    <configuration>
+			        <release>11</release>
+			    </configuration>            
             </plugin>
             <plugin>
                 <groupId>org.jacoco</groupId>
diff --git a/trampoline/pom.xml b/trampoline/pom.xml
index e6f2e620afac..1bd675c30576 100644
--- a/trampoline/pom.xml
+++ b/trampoline/pom.xml
@@ -51,7 +51,7 @@
         <dependency>
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>
-            <version>1.16.18</version>
+            <version>1.18.2</version>
         </dependency>
 
 
