Switch to 'runtimeClasspath' instead of resolve 'implementation' configuration (#433)

In PR #432 the build.gradle was updated to run on Gradle 7, part of the change consisted in
forcing the resolution of 'implementation' configuration to use it in the listing of dependencies.
This could be assolved by the 'runtimeClasspath' without forcing the resolution which smells like a trick.

Relates #432

Author: andsel

build.gradle

@@ -56,14 +56,12 @@ task run (type: JavaExec, dependsOn: classes){
 }
 
 task generateGemJarRequiresFile {
-    configurations.implementation.canBeResolved = true
-
     doLast {
         File jars_file = file('lib/logstash-input-beats_jars.rb')
             jars_file.newWriter().withWriter { w ->
                 w << "# AUTOGENERATED BY THE GRADLE SCRIPT. DO NOT EDIT.\n\n"
                     w << "require \'jar_dependencies\'\n"
-                    configurations.implementation.allDependencies.each {
+                    configurations.runtimeClasspath.allDependencies.each {
                         w << "require_jar(\'${it.group}\', \'${it.name}\', \'${it.version}\')\n"
                     }
                 w << "require_jar(\'${project.group}\', \'${project.name}\', \'${project.version}\')\n"
@@ -74,8 +72,8 @@ task generateGemJarRequiresFile {
 task vendor {
     doLast {
         String vendorPathPrefix = "vendor/jar-dependencies"
-            configurations.implementation.allDependencies.each { dep ->
-                File f = configurations.implementation.filter { it.absolutePath.contains("${dep.group}/${dep.name}/${dep.version}") }.singleFile
+            configurations.runtimeClasspath.allDependencies.each { dep ->
+                File f = configurations.runtimeClasspath.filter { it.absolutePath.contains("${dep.group}/${dep.name}/${dep.version}") }.singleFile
                     String groupPath = dep.group.replaceAll('\\.', '/')
                     File newJarFile = file("${vendorPathPrefix}/${groupPath}/${dep.name}/${dep.version}/${dep.name}-${dep.version}.jar")
                     newJarFile.mkdirs()