language/java: add support for OpenJDK formula

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

@@ -4,17 +4,25 @@ module Language
   module Java
     def self.system_java_home_cmd(version = nil)
       version_flag = " --version #{version}" if version
-      "/usr/libexec/java_home#{version_flag}"
+      "/usr/libexec/java_home#{version_flag} --failfast 2>/dev/null"
     end
     private_class_method :system_java_home_cmd
 
     def self.java_home(version = nil)
+      f = find_openjdk_formula(version)
+      return f.opt_libexec/"openjdk.jdk/Contents/Home" if f
+
       cmd = system_java_home_cmd(version)
-      Pathname.new Utils.popen_read(cmd).chomp
+      path = Utils.popen_read(cmd).chomp
+
+      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
   end

Library/Homebrew/language/java.rb

@@ -2,7 +2,31 @@
 
 module Language
   module Java
+    def self.find_openjdk_formula(version = nil)
+      can_be_newer = version&.end_with?("+")
+      version = version.to_i
+
+      openjdk = Formula["openjdk"]
+      [openjdk, *openjdk.versioned_formulae].find do |f|
+        next false unless f.any_version_installed?
+
+        unless version.zero?
+          major = f.version.to_s[/\d+/].to_i
+          next false if major < version
+          next false if major > version && !can_be_newer
+        end
+
+        true
+      end
+    rescue FormulaUnavailableError
+      nil
+    end
+    private_class_method :find_openjdk_formula
+
     def self.java_home(version = nil)
+      f = find_openjdk_formula(version)
+      return f.opt_libexec if f
+
       req = JavaRequirement.new [*version]
       raise UnsatisfiedRequirements, req.message unless req.satisfied?