Gradle compile dependencies not included in Jar - plugins

Question

I have a jar, build-plugins.jar with a gradle plugin that is build with this in build.gradle:
apply plugin 'java'
dependencies {
compile gradleApi()
compile localGroovy()
compile('eviware:maven-soapui-plugin:4.5.1')
compile('org.antlr:stringtemplate:4.0.2')
compile('commons-io:commons-io:2.4')
compile('joda-time:joda-time:2.1')
}
This builds build-plugins.jar. And the project that consumes the plugin references the plugin jar by file
apply plugin 'thepluginwahoo'
buildscript {
dependencies {
classpath 'org.jfrog.buildinfo:build-info-extractor-gradle:2.2.1'
classpath files('/path/to/build-plugins.jar')
}
}
The problem is when I run any task of the second project, I get "class proxy could not be created for class xyz" with the root cause being that the four dependencies (joda-time, commons-io, stringtemplate, maven-soapui-plugin) are not there. If I add the dependencies to the plugin-consuming project then it works just fine:
apply plugin 'thepluginwahoo'
buildscript {
dependencies {
classpath 'org.jfrog.buildinfo:build-info-extractor-gradle:2.2.1'
classpath files('/path/to/build-plugins.jar')
classpath 'eviware:maven-soapui-plugin:4.5.1'
classpath 'org.antlr:stringtemplate:4.0.2'
classpath 'joda-time:joda-time:2.1'
classpath 'commons-io:commons-io:2.4'
}
}
My question is why don't the classes of the "compile" dependencies in the plugin project appear in the plugin-consuming project when the jar is included in the classpath of the buildscript of the plugin-consuming project.

Answer 1

Jars typically do not contain their dependencies. Instead, they are published to a repository along with some kind of metadata descriptor (pom.xml or ivy.xml) which describes the artifact's dependencies. When you refer to the jar file directly as a dependency, Gradle has no way of knowing what its transitive dependencies are. You have a couple of ways to deal with this:
Publish your plugin jar to a repository, along with the necessary metadata (which Gradle will do for you) and bring it in as an external module dependency
Explicitly declare the plugin's transitive dependencies using a client module dependency.
Use something like the Gradle fatjar or shadow plugins to bundle dependencies within your jar.