Added Java 11

runtimes/openjdk11_headless-java.nix

@@ -0,0 +1,57 @@
+{pkgs, piston, ...}:
+let
+    # Put your package here, preferibly from nixpkgs.
+    pkg = pkgs.openjdk11_headless; # this may be incorrect - it is guessed
+in piston.mkRuntime {
+    # Name of the language implemented by this runtime
+    language = "java";
+
+    # The version of the language
+    # Usually this is specified on the package
+    version = pkg.version;
+
+    # Name of the runtime
+    # This line should be kept if the runtime differs from the language
+    runtime = "openjdk11_headless";
+
+    aliases = [
+    ];
+
+    # This is the lines of a shell script to evaluate a file at $1
+    # The remaining arguments are the arguments to launch the application with
+    # The CWD of this script is a temp directory for a job
+    #
+    # If the compile stage is used, $1 still contains the name of the source file.
+    # It is up to your script to determine the filename of the emitted binary
+    #
+    # No shebang needs to be added to this - that is done automatically.
+    run = ''
+    mv $1 $1.java
+    filename=$1.java
+    shift
+    ${pkg}/bin/java $filename "$@"
+    '';
+
+    # Specify a list of tests.
+    # These should output "OK" to STDOUT if everything looks good
+    #
+    # Run the following command to test the package:
+    # $ ./piston test openjdk11_headless-java
+    tests = [
+        (piston.mkTest {
+            files = {
+                "test.java" = ''
+                    public class HelloWorld {
+                        public static void main(String[] args) {
+                            System.out.println("OK");
+                        }
+                    }
+                '';
+            };
+            args = [];
+            stdin = "";
+            packages = [];
+            main = "test.java";
+        })
+    ];
+}