maven: use default jdk

While builds using maven are relatively likely to target jdk8,
they typically support building using default jdk.

The main exception is the default jdk no longer supports targeting
JRE's before version 8. For projects that do that we can override the
jdk version for the maven used there.

pkgs/development/java-modules/junit/default.nix

@@ -1,12 +1,17 @@
-{ lib, pkgs, mavenbuild, fetchMaven }:
+{ lib, pkgs, mavenbuild, fetchMaven, maven, jdk8 }:
 
 with pkgs.javaPackages;
 
 let
   poms = import (../poms.nix) { inherit fetchMaven; };
   collections = import (../collections.nix) { inherit pkgs; };
+  mavenbuild-jdk8 = mavenbuild.override {
+    maven = maven.override {
+      jdk = jdk8;
+    };
+  };
 in rec {
-  junitGen = { mavenDeps, sha512, version }: mavenbuild {
+  junitGen = { mavenDeps, sha512, version }: mavenbuild-jdk8 {
     inherit mavenDeps sha512 version;
 
     name = "junit-${version}";

pkgs/development/java-modules/maven-hello/default.nix

@@ -1,11 +1,21 @@
-{ lib, pkgs, mavenbuild }:
+{ lib
+, pkgs
+, mavenbuild
+, maven
+, jdk8
+}:
 
 with pkgs.javaPackages;
 
 let
   poms = import ../poms.nix { inherit fetchMaven; };
+  mavenbuild-jdk8 = mavenbuild.override {
+    maven = maven.override {
+      jdk = jdk8;
+    };
+  };
 in rec {
-  mavenHelloRec = { mavenDeps, sha512, version, skipTests ? true, quiet ? true }: mavenbuild {
+  mavenHelloRec = { mavenDeps, mavenbuild, sha512, version, skipTests ? true, quiet ? true }: mavenbuild {
     inherit mavenDeps sha512 version skipTests quiet;
 
     name = "maven-hello-${version}";
@@ -31,6 +41,7 @@ in rec {
     mavenDeps = [];
     sha512 = "3kv5z1i02wfb0l5x3phbsk3qb3wky05sqn4v3y4cx56slqfp9z8j76vnh8v45ydgskwl2vs9xjx6ai8991mzb5ikvl3vdgmrj1j17p2";
     version = "1.0";
+    mavenbuild = mavenbuild-jdk8;
   };
 
   mavenHello_1_1 = mavenHelloRec {
@@ -39,5 +50,6 @@ in rec {
     version = "1.1";
     skipTests = false;
     quiet = false;
+    mavenbuild = mavenbuild-jdk8;
   };
 }