Fix public API method missing Javadoc.

Signed-off-by: Chris Bono <chris.bono@broadcom.com>

Author: onobc

src/main/java/org/springframework/data/redis/connection/ReactiveStreamCommands.java

@@ -2044,6 +2044,15 @@ default Mono<Long> xTrim(ByteBuffer key, long count, boolean approximateTrimming
 				.map(NumericResponse::getOutput);
 	}
 
+	/**
+	 * Trims the stream to {@code count} elements.
+	 *
+	 * @param key the stream key.
+	 * @param options the trim options
+	 * @return {@link Mono} emitting the number of removed entries.
+	 * @since 4.1
+	 * @see <a href="https://redis.io/commands/xtrim">Redis Documentation: XTRIM</a>
+	 */
 	default Mono<Long> xTrim(ByteBuffer key, XTrimOptions options) {
 
 		Assert.notNull(key, "Key must not be null");