Fix jedis#hdel docs (#3290)

* Fix jedis#hdel docs

* Apply suggestions from code review

---------

Co-authored-by: M Sazzadul Hoque <[email protected]>

Author: keeferrourke

src/main/java/redis/clients/jedis/Jedis.java

@@ -5687,13 +5687,15 @@ public boolean hexists(final String key, final String field) {
   }
 
   /**
-   * Remove the specified field from an hash stored at key.
+   * Remove the specified field(s) from a hash stored at key. Specified fields that do not exist
+   * within this hash are ignored.
    * <p>
    * <b>Time complexity:</b> O(1)
    * @param key
    * @param fields
-   * @return If the field was present in the hash it is deleted and 1 is returned, otherwise 0 is
-   *         returned and no operation is performed.
+   * @return The number of fields that were removed from the hash, not including specified but
+   *         non-existing fields. If key does not exist, it is treated as an empty hash and this
+   *         command returns 0.
    */
   @Override
   public long hdel(final String key, final String... fields) {

src/test/java/redis/clients/jedis/commands/jedis/HashesCommandsTest.java

@@ -200,7 +200,7 @@ public void hexists() {
 
   @Test
   public void hdel() {
-    Map<String, String> hash = new HashMap<String, String>();
+    Map<String, String> hash = new HashMap<>();
     hash.put("bar", "car");
     hash.put("car", "bar");
     jedis.hmset("foo", hash);
@@ -211,7 +211,7 @@ public void hdel() {
     assertNull(jedis.hget("foo", "bar"));
 
     // Binary
-    Map<byte[], byte[]> bhash = new HashMap<byte[], byte[]>();
+    Map<byte[], byte[]> bhash = new HashMap<>();
     bhash.put(bbar, bcar);
     bhash.put(bcar, bbar);
     jedis.hmset(bfoo, bhash);
@@ -220,6 +220,13 @@ public void hdel() {
     assertEquals(0, jedis.hdel(bfoo, bfoo));
     assertEquals(1, jedis.hdel(bfoo, bbar));
     assertNull(jedis.hget(bfoo, bbar));
+
+    // Deleting multiple fields returns the right value.
+    jedis.hmset("foo", hash);
+    assertEquals(2, jedis.hdel("foo", "bar", "car", "dne"));
+
+    jedis.hmset(bfoo, bhash);
+    assertEquals(2, jedis.hdel(bfoo, bbar, bcar, bbar1));
   }
 
   @Test