JDK 1.7.0_40 or newer - Oh yeah!

[INFO] --- maven-enforcer-plugin:1.1:enforce (enforce-java) @ jetty-project ---
[WARNING] Rule 1: org.apache.maven.plugins.enforcer.RequireJavaVersion failed with message:
[ERROR] OLD JDK [1.7.0_09] in use. Jetty 9.2.2.v20140723 requires JDK 1.7.0_40 or newer

https://webtide.com/jetty-9-features/
Java 7 – We have removed some areas of abstraction within jetty in order to take advantage of improved APIs in the JVM regarding concurrency and nio, this leads to a leaner implementation and improved performance.