Migrate supported java version from 1.6 to 1.8

[Hamlin-Li]

Hi,

Can I have a discussion about the supported jdk versions of zstd-jni?
In the build.sbt, jdk1.6 is still supported:

javacOptions ++= Seq("--release", "6", "-Xlint:unchecked")
...
doc / javacOptions := Seq("--release", "6")
...
OsgiKeys.requireCapability := "osgi.ee;filter:=\"(&(osgi.ee=JavaSE)(version>=1.6))\""

I'm not sure if this is necessary, but seems this blocks the usage of zstd-jni in jdk 17/21 and later?

$ javac -version
javac 17.0.2
hamlin@hamlin:~/workspace/tools$ javac --release 6 Test.java
error: release version 6 not supported
Usage: javac <options> <source files>
use --help for a list of possible options

Do we have a plan to migrate the supportted jdk version from 1.6 to 1.8? If positive, this is the pr to do it.

Thanks!

[luben]

Yes, I think we should update the minimum supported version.

[Hamlin-Li]

Thanks for your review!