Fix bug which caused javadoc-agg to use the task's group, rather than the maven group.

Author: nedtwigg

src/main/resources/base/javadoc-agg.gradle

@@ -5,6 +5,7 @@ def javadocAgg   = 干.proj('javadoc_agg', 'space-delimited list of projects con
 def git_url      = 干.proj('git_url', 'the git url with no protocol, e.g.: github.com/diffplug/blowdryer')
 def javadocLinks = 干.proj('javadoc_links', "space-delimited links, if you add '/package-list' to the urls you should get a package list").split()
 group              = 干.proj('maven_group',    'the maven group, recommend com.diffplug')
+def maven_group    = group
 def license        = 干.proj('license', 'supported: apache')
 def license_name     = 干.prop('base/maven', "${license}_name")
 def license_url      = 干.prop('base/maven', "${license}_url")
@@ -37,7 +38,7 @@ def rootJavadoc = tasks.register('javadoc', Javadoc) {
 
 	// copied from base/maven
 	def makeLink = { url, text -> "<a href=\"${url}\" style=\"text-transform: none;\">${text}</a>" }
-	def javadocInfo = '<h2>' + makeLink("https://${git_url}", "${group}:${maven_artifact}:${version}") +
+	def javadocInfo = '<h2>' + makeLink("https://${git_url}", "${maven_group}:${maven_artifact}:${version}") +
 			' by ' + makeLink('https://www.diffplug.com', 'DiffPlug') + '</h2>';
 	// Where it's possible to name parameters and methods clearly enough
 	// that javadoc is not necessary, why make the code bigger?