Some deprecation warnings when building with gradlew

[barrybecker4]

This is minor, but I noticed a couple of deprecation warnings when I built using "./gradlew build".

A problem was found with the configuration of task ':shadowJar'. Registering invalid inputs and outputs via TaskInputs and TaskOutputs methods has been deprecated and is scheduled to be removed in Gradle 5.0.
 - No value has been specified for property 'mainClassName'.
The SimpleWorkResult type has been deprecated and is scheduled to be removed in Gradle 5.0. Please use WorkResults.didWork() instead.
:startShadowScripts
Using TaskInputs.file() with something that doesn't resolve to a File object has been deprecated and is scheduled to be removed in Gradle 5.0. Use TaskInputs.files() instead.