Sample Spring app is broken in Jetty container

The version of Jackson currently used by the Spring sample project has an embedded `module-info` for Java 9 JMS which causes Jetty to throw an exception when scanning for attributes. We would need to upgrade to at least Jetty 9.4.x which has support for Java 9, even if we're running on a Java 8 runtime. I did attempt that upgrade last night but was having trouble getting the Spring mappings to work so that will require additional work. However, downgrading Jackson back to 2.9.x works around the issue.

See: https://github.com/eclipse/jetty.project/issues/1692

Locate the dependency declarations and Spring mappings for the sample project, then reproduce the Jetty startup failure described in the issue. Compare the current Jackson and Jetty versions and verify that the sample starts in Jetty without the module-scanning exception and that its Spring mappings still work.

Written by the indexing model from the issue text.