message: fix: export java exec
diff: @@ -20,7 +20,7 @@ import * as Net from "@xmcl/net";
  import { GotBodyFn, GotInstance } from "got";
  const got: GotInstance<GotBodyFn<string>> = Net.got;
  -import Util, { MinecraftFolder, MinecraftLocation } from "@xmcl/util";
  +import Util, { MinecraftFolder, MinecraftLocation, JavaExecutor } from "@xmcl/util";
  export { ResolvedLibrary, ResolvedNative, ResolvedVersion, PartialResolvedVersion, LibraryInfo, VersionDiagnosis } from "@xmcl/version";
  export { World } from "@xmcl/world";
  