Bump to Gradle 6.5.1 and add japicmp

[simonbasle]

• Bump to Gradle 6.5.1

  • remove OsgiHelper import and usage
  • bump artifactory to 4.15.2
  • add bnd plugin id 'biz.aQute.bnd.builder' version '5.0.1' apply false
  • avoid generating module metadata (see snippet below)
  • apply plugin: 'biz.aQute.bnd.builder'
  • replace bundleImportPackages with a bndOptions string[][] array (see below)
  • configure bnd with the bndOptions in the jar task: bnd(bndOptions)

• add plugin id "me.champeau.gradle.japicmp" version "0.2.6"

  • add plugin id "de.undercouch.download" version "3.4.3"
  • check.dependsOn japicmp
  • add downloadBaseline and japicmp tasks (without the Rule, only simplified exclusions)
  • add compatibleVersion=0.1.0.RELEASE to gradle.properties

To avoid generating module metadata:

tasks.withType(GenerateModuleMetadata) {
  enabled = false
}

bnd options:

  ext.bndOptions = [
    "Export-Package": [
      "!*internal*",
      "reactor.*"
    ].join(","),
    "Import-Package": [
      "!javax.annotation",
      "*"
    ].join(","),
    "Bundle-Name" : "reactor-pool",
    "Bundle-SymbolicName" : "io.projectreactor.addons.reactor-pool"
  ]