extend/pathname: use Java.overridable_java_home_env in write_jar_script

Library/Homebrew/compat/language/java.rb

@@ -5,7 +5,8 @@ module Language
     class << self
       module Compat
         def java_home_cmd(version = nil)
-          odeprecated "Language::Java::java_home_cmd", "Language::Java::java_home"
+          odeprecated "Language::Java.java_home_cmd",
+                      "Language::Java.java_home or Language::Java.overridable_java_home_env"
 
           # macOS provides /usr/libexec/java_home, but Linux does not.
           return system_java_home_cmd(version) if OS.mac?

Library/Homebrew/extend/os/mac/language/java.rb

@@ -18,12 +18,12 @@ module Language
       Pathname.new path if path.present?
     end
 
-    # @private
     def self.java_home_shell(version = nil)
       f = find_openjdk_formula(version)
       return (f.opt_libexec/"openjdk.jdk/Contents/Home").to_s if f
 
       "$(#{system_java_home_cmd(version)})"
     end
+    private_class_method :java_home_shell
   end
 end

Library/Homebrew/extend/pathname.rb

@@ -370,12 +370,8 @@ class Pathname
 
   # Writes an exec script that invokes a Java jar
   def write_jar_script(target_jar, script_name, java_opts = "", java_version: nil)
-    mkpath
-    java_home = ("JAVA_HOME=\"#{Language::Java.java_home_shell(java_version)}\" " if java_version)
-    join(script_name).write <<~SH
-      #!/bin/bash
-      #{java_home}exec java #{java_opts} -jar #{target_jar} "$@"
-    SH
+    (self/script_name).write_env_script "java #{java_opts} -jar #{target_jar}",
+                                        Language::Java.overridable_java_home_env(java_version)
   end
 
   def install_metafiles(from = Pathname.pwd)

Library/Homebrew/language/java.rb

@@ -33,10 +33,10 @@ module Language
       req.java_home
     end
 
-    # @private
     def self.java_home_shell(version = nil)
       java_home(version).to_s
     end
+    private_class_method :java_home_shell
 
     def self.java_home_env(version = nil)
       { JAVA_HOME: java_home_shell(version) }