Give the Provider constructor parameter of KeyStore unspecified n…

…ullness.

As discussed in
#29 (comment), I can't
tell whether it should be `@Nullable` or not.

The way to give it unspecified nullness is to use `@NullUnmarked`. To at
least keep non-null types for the _other_ two parameters, I've added
`@NonNull` on them.

This would be slightly simpler with [a type-use annotation for
unspecified nullness](jspecify/jspecify#137).
But the approach described above works fine (if somewhat verbosely),
since there this API doesn't use parametric nullness.

src/java.base/share/classes/java/security/KeyStore.java

@@ -25,7 +25,9 @@
 
 package java.security;
 
+import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.NullUnmarked;
 import org.jspecify.annotations.Nullable;
 
 import java.io.*;
@@ -814,7 +816,8 @@ public String toString() {
      * @param provider the provider.
      * @param type the keystore type.
      */
-    protected KeyStore(KeyStoreSpi keyStoreSpi, Provider provider, String type)
+    @NullUnmarked // https://github.com/jspecify/jdk/pull/29#issuecomment-1653637366
+    protected KeyStore(@NonNull KeyStoreSpi keyStoreSpi, Provider provider, @NonNull String type)
     {
         this.keyStoreSpi = keyStoreSpi;
         this.provider = provider;