Polishing and minor refactoring

Closes gh-31202

spring-web/src/main/java/org/springframework/http/HttpStatusCode.java

@@ -88,14 +88,6 @@ public sealed interface HttpStatusCode extends Serializable permits DefaultHttpS
 		return value() == other.value();
 	}
 
-	/**
-	 * Checks whether this status code is a well-known HTTP status code or not
-	 * @return {@code true} if the status code corresponds to a standard HTTP status code, {@code false} otherwise
-	 */
-	default boolean isWellKnown() {
-		return HttpStatus.resolve(this.value()) != null;
-	}
-
 	/**
 	 * Return an {@code HttpStatusCode} object for the given integer value.
 	 * @param code the status code as integer