[bug#39742] [PATCH 1/7] gnu: java-openjfx-build: Add helpful patch.

[Alexey Abramov <levenson@mmer.org>]

* gnu/packages/java.scm: Add patch
* gnu/packages/patches/java-openjfx-build-get_guix_jdk_version.patch: New
  file. Allows you to run gradlew to run properly. Useful for debugging.
---
 gnu/packages/java.scm                              |  3 ++-
 .../java-openjfx-build-get_guix_jdk_version.patch  | 14 ++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 gnu/packages/patches/java-openjfx-build-get_guix_jdk_version.patch

diff --git a/gnu/packages/java.scm b/gnu/packages/java.scm
index 9371901e1f..01541ee419 100644
--- a/gnu/packages/java.scm
+++ b/gnu/packages/java.scm
@@ -2355,7 +2355,8 @@ new Date();"))
               (file-name (string-append name "-" version "-checkout"))
               (sha256
                (base32
-                "0yg38mwpivswccv9n96k06x3iv82i4px1a9xg9l8dswzwmfj259f"))))
+                "0yg38mwpivswccv9n96k06x3iv82i4px1a9xg9l8dswzwmfj259f"))
+              (patches (search-patches "java-openjfx-build-get_guix_jdk_version.patch"))))
     (build-system ant-build-system)
     (arguments
      `(#:jar-name "java-openjfx.jar"
diff --git a/gnu/packages/patches/java-openjfx-build-get_guix_jdk_version.patch b/gnu/packages/patches/java-openjfx-build-get_guix_jdk_version.patch
new file mode 100644
index 0000000000..214ef9949c
--- /dev/null
+++ b/gnu/packages/patches/java-openjfx-build-get_guix_jdk_version.patch
@@ -0,0 +1,14 @@
+--- a/build.gradle
++++ b/build.gradle
+@@ -742,9 +742,9 @@
+     if (inStream.readLine() != null) {
+         String v = inStream.readLine();
+         if (v != null) {
+-            int ib = v.indexOf(" (build ");
++            int ib = v.indexOf(" (guix build ");
+             if (ib != -1) {
+-                String ver = v.substring(ib + 8, v.size() - 1);
++                String ver = v.substring(ib + 13, v.size() - 1);
+ 
+                 defineProperty("jdkRuntimeVersion", ver)
+                 defineProperty("jdkVersion", jdkRuntimeVersion.split("-")[0])
-- 
2.24.1