use gradle java-platform in grpc-bom; Fixes #5530 (#11875)

* use gradle java-platform in grpc-bom; Fixes #5530 * fix withXml * explicitly exclude grpc-compiler

Author: panchenko

bom/build.gradle

@@ -1,40 +1,32 @@
 plugins {
+ id 'java-platform'
  id "maven-publish"
 }
 
 description = 'gRPC: BOM'
 
+gradle.projectsEvaluated {
+ def projectsToInclude = rootProject.subprojects.findAll {
+ return it.name != 'grpc-compiler'
+ && it.plugins.hasPlugin('java')
+ && it.plugins.hasPlugin('maven-publish')
+ && it.tasks.findByName('publishMavenPublicationToMavenRepository')?.enabled
+ }
+ dependencies {
+ constraints {
+ projectsToInclude.each { api it }
+ }
+ }
+}
+
 publishing {
  publications {
  maven(MavenPublication) {
- // remove all other artifacts since BOM doesn't generates any Jar
- artifacts = []
-
+ from components.javaPlatform
  pom.withXml {
- // Generate bom using subprojects
- def internalProjects = [
- project.name,
- 'grpc-compiler',
- ]
-
- def dependencyManagement = asNode().appendNode('dependencyManagement')
- def dependencies = dependencyManagement.appendNode('dependencies')
- rootProject.subprojects.each { subproject ->
- if (internalProjects.contains(subproject.name)) {
- return
- }
- if (!subproject.hasProperty('publishMavenPublicationToMavenRepository')) {
- return
- }
- if (!subproject.publishMavenPublicationToMavenRepository.enabled) {
- return
- }
- def dependencyNode = dependencies.appendNode('dependency')
- dependencyNode.appendNode('groupId', subproject.group)
- dependencyNode.appendNode('artifactId', subproject.name)
- dependencyNode.appendNode('version', subproject.version)
- }
+ def dependencies = asNode().dependencyManagement.dependencies.last()
  // add protoc gen (produced by grpc-compiler with different artifact name)
+ // not sure how to express "<type>pom</type>" in gradle, kept in XML
  def dependencyNode = dependencies.appendNode('dependency')
  dependencyNode.appendNode('groupId', project.group)
  dependencyNode.appendNode('artifactId', 'protoc-gen-grpc-java')