[MINOR][BUILD] Fix about 15 misc build warnings

This addresses about 15 miscellaneous warnings that appear in the current build.

No functional changes, it just slightly reduces the amount of extra warning output.

No.

Existing tests, run manually.

Closes #25852 from srowen/BuildWarnings.

Authored-by: Sean Owen <[email protected]>
Signed-off-by: Dongjoon Hyun <[email protected]>

Author: srowen

common/kvstore/src/main/java/org/apache/spark/util/kvstore/InMemoryStore.java

@@ -252,7 +252,7 @@ private static <T> Predicate<? super T> getPredicate(
 
         return (value) -> set.contains(indexValueForEntity(getter, value));
       } else {
-        HashSet<Comparable> set = new HashSet<>(values.size());
+        HashSet<Comparable<?>> set = new HashSet<>(values.size());
         for (Object key : values) {
           set.add(asKey(key));
         }

common/kvstore/src/main/java/org/apache/spark/util/kvstore/KVTypeInfo.java

@@ -124,7 +124,7 @@ interface Accessor {
 
     Object get(Object instance) throws ReflectiveOperationException;
 
-    Class getType();
+    Class<?> getType();
   }
 
   private class FieldAccessor implements Accessor {
@@ -141,7 +141,7 @@ public Object get(Object instance) throws ReflectiveOperationException {
     }
 
     @Override
-    public Class getType() {
+    public Class<?> getType() {
       return field.getType();
     }
   }
@@ -160,7 +160,7 @@ public Object get(Object instance) throws ReflectiveOperationException {
     }
 
     @Override
-    public Class getType() {
+    public Class<?> getType() {
       return method.getReturnType();
     }
   }