Merge pull request #2244 from jonchang/java

java_requirement: don't consider macOS Java stub

Library/Homebrew/extend/os/mac/requirements/java_requirement.rb

@@ -12,7 +12,9 @@ class JavaRequirement < Requirement
     javas = []
     javas << Pathname.new(ENV["JAVA_HOME"])/"bin/java" if ENV["JAVA_HOME"]
     javas << java_home_cmd
-    javas << which("java")
+    which_java = which("java")
+    # /usr/bin/java is a stub on macOS
+    javas << which_java if which_java.to_s != "/usr/bin/java"
     javas
   end