Prior to this commit, GroovyDynamicElementReader was implemented in
Groovy, which required that developers have Groovy language support
installed and configured in their IDEs.
This commit ports GroovyDynamicElementReader from Groovy to Java,
making the compilation much simpler and allowing developers to open the
project in Eclipse or VSCode (or other IDEs without Groovy support)
without compiler errors.
This commit also converts related tests from Groovy to Java.
Closes gh-27945
f7c3706361