Add missing contraint values.

java/constraints/BUILD

diff --git a/java/constraints/BUILD b/java/constraints/BUILD
index 1620a55..fbc5407 100644
--- a/java/constraints/BUILD
+++ b/java/constraints/BUILD
@@ -31,6 +31,11 @@
     constraint_setting = ":runtime",
 )
 
+constraint_value(
+    name = "jdk12",
+    constraint_setting = ":runtime",
+)
+
 constraint_setting(name = "language")
 
 # visibility
@@ -43,3 +48,23 @@
     name = "java8",
     constraint_setting = ":language",
 )
+
+constraint_value(
+    name = "java9",
+    constraint_setting = ":language",
+)
+
+constraint_value(
+    name = "java10",
+    constraint_setting = ":language",
+)
+
+constraint_value(
+    name = "java11",
+    constraint_setting = ":language",
+)
+
+constraint_value(
+    name = "java12",
+    constraint_setting = ":language",
+)