Create a Java Persistence API (JPA) entity class 'Car' for cars. A car should have the following attributes: name of the model (e.g., Beetle), manufacturer (e.g., Volkswagen), price, year of production. Create an (ordinary, non-servlet) Java class with a method for storing an object of class Car in a database, using JPA. The car object should be given as the method parameter. In case that car already exists in the database, the respective entry in the database should be updated. Please provide only Java code for answers with comments explaining code if possible.