Build: Turn on license header checks

This is dependent on elastic/elasticsearchelastic/elasticsearch#19589. It also fixes the
existing files that either were missing the license header or had the
open source license header.

Original commit: elastic/x-pack-elasticsearch@2642c20381

elasticsearch/build.gradle

@@ -1,3 +1,5 @@
+import org.elasticsearch.gradle.precommit.LicenseHeadersTask
+
 File checkstyleSuppressions = file('checkstyle_suppressions.xml')
 subprojects {
   tasks.withType(Checkstyle) {
@@ -7,4 +9,9 @@ subprojects {
       suppressions: checkstyleSuppressions
     ]
   }
+
+  tasks.withType(LicenseHeadersTask.class) {
+    approvedLicenses = ['Elasticsearch Confidential']
+    additionalLicense 'ESCON', 'Elasticsearch Confidential', 'ELASTICSEARCH CONFIDENTIAL'
+  }
 }

elasticsearch/license/build.gradle

@@ -3,7 +3,5 @@ subprojects {
     project.forbiddenPatterns {
       exclude '**/*.key'
     }
-    // someone figure out what the x-plugins logic should be
-    project.licenseHeaders.enabled = false
   }
 }

elasticsearch/qa/build.gradle

@@ -1,6 +0,0 @@
-subprojects {
-  tasks.withType(org.elasticsearch.gradle.precommit.LicenseHeadersTask) {
-    // someone figure out what the x-plugins logic should be
-    project.licenseHeaders.enabled = false
-  }
-}

elasticsearch/x-pack/build.gradle

@@ -19,7 +19,10 @@ ext.versions = [
 // TODO: fix this! https://github.com/elastic/x-plugins/issues/1066
 ext.compactProfile = 'full'
 
-dependencyLicenses.enabled = false
+licenseHeaders {
+  approvedLicenses << 'BCrypt (BSD-like)'
+  additionalLicense 'BCRYP', 'BCrypt (BSD-like)', 'Copyright (c) 2006 Damien Miller <djm@mindrot.org>'
+}
 
 dependencies {
   // license deps
@@ -232,9 +235,6 @@ thirdPartyAudit.excludes = [
     'javax.activation.UnsupportedDataTypeException'    
 ]
 
-// someone figure out what the x-plugins logic should be
-licenseHeaders.enabled = false
-
 modifyPom { MavenPom pom ->
   pom.withXml { XmlProvider xml ->
     // first find if we have dependencies at all, and grab the node