ENT-4595 Add git based version (#5799)

* ENT-4595 Allow publishing a version with a git based version string

* ENT-4595 rename option and add comment

* ENT-4595 Fix groovy/Java string incompatibility

* Remove Constants.kt so it gets regenerated on a fresh check-out.

* Add Constants.kt to .gitignore

* Reverted deletion of Constants.kt as it would cause problems for IntelliJ users

* Reverted logging Constants.kt file to how it was before

* Undid template change too

* Reverted template file properly this time.

.gitignore

@@ -103,4 +103,4 @@ virtualenv/
 # Files you may find useful to have in your working directory.
 PLAN
 NOTES
-TODO
+TODO

build.gradle

@@ -11,7 +11,9 @@ buildscript {
     file("$projectDir/constants.properties").withInputStream { constants.load(it) }
 
     // Our version: bump this on release.
-    ext.corda_release_version = constants.getProperty("cordaVersion")
+    ext.baseVersion = constants.getProperty("cordaVersion")
+    ext.versionSuffix = constants.getProperty("versionSuffix")
+
     ext.corda_platform_version = constants.getProperty("platformVersion")
     ext.gradle_plugins_version = constants.getProperty("gradlePluginsVersion")
 
@@ -186,7 +188,8 @@ plugins {
     // Add the shadow plugin to the plugins classpath for the entire project.
     id 'com.github.johnrengelman.shadow' version '2.0.4' apply false
     id "com.gradle.build-scan" version "2.2.1"
-}
+    id "org.ajoberstar.grgit" version "4.0.0"
+ }
 
 ext {
 }
@@ -198,6 +201,20 @@ apply plugin: 'maven-publish'
 apply plugin: 'com.jfrog.artifactory'
 apply plugin: "com.bmuschko.docker-remote-api"
 
+
+// If the command line project option -PversionFromGit is added to the gradle invocation, we'll resolve 
+// the latest git commit hash and timestamp and create a version postfix from that
+if (project.hasProperty("versionFromGit")){
+    ext.versionSuffix = "${grgit.head().dateTime.format("yyyyMMdd_HHmmss")}-${grgit.head().abbreviatedId}"
+}
+
+// Need the `toString()` call on these, because they need to be converted from GStringImpl to Java Strings.
+if (ext.versionSuffix != ""){
+    ext.corda_release_version = "${ext.baseVersion}-${ext.versionSuffix}".toString()
+} else {
+    ext.corda_release_version = "${ext.baseVersion}".toString()
+}
+
 // We need the following three lines even though they're inside an allprojects {} block below because otherwise
 // IntelliJ gets confused when importing the project and ends up erasing and recreating the .idea directory, along
 // with the run configurations. It also doesn't realise that the project is a Java 8 project and misconfigures

constants.properties

@@ -2,7 +2,9 @@
 # because some versions here need to be matched by app authors in
 # their own projects. So don't get fancy with syntax!
 
-cordaVersion=4.3-SNAPSHOT
+
+cordaVersion=4.3
+versionSuffix=SNAPSHOT
 gradlePluginsVersion=5.0.4
 kotlinVersion=1.2.71
 java8MinUpdateVersion=171