In this assignment we get practice using ArrayLists and HashMaps and how to query them. There are two classes. The ResearchPaper class is the record, and PaperDBModel is the database. You are to finish PaperDBModel by properly storing and retrieving the records in ArrayLists and HashMaps. You are given some test records in a file paper.txt. Most IDE's are particular about where they read files from. If you are using IntelliJ, you must copy and paste paper.txt into the project folder (that is, the highest level folder that contains your src, out, and .idea folders). You are encouraged to add records to paper.txt for testing purposes (see question 5). 1) [4 marks] Open PaperDBModel.java. All the data structures you need are listed as member variables. Instantiate each of them in the constructor. 2) [8 marks] Complete getResearchPaper, getPapersByAuthor, getPapersByConference, and getPapersByKeyword. Descriptions are in the comments. Note the return type. 3) [20 marks] Complete AddResearchPaper and Remove ResearchPaper (most of the work is here). Each paper should be added or removed from all data structures. 4)[12 marks] Complete a) getPapersByAuthor And Conference and b) getPapersByAuthors. These methods should return all papers that a) were published in the given conference and have the given author listed, and b) have all the given authors listed. 5) [8 marks] - This question is no longer necessary. These tests have been given to you in PaperDBModelTester.java, and everyone who submits the assignment will automatically get 8 marks for this question. The static main method loads some records from a file (paper.txt) and prints them to the console. Write tests for the methods above. Simply printing them out is enough, but there must be records that both meet the description of the method and those that do not so that we can determine the method works properly. For example, in getPapersByAuthor you must have at least one record with the author given as argument, as well as at least one record without. You can add records to paper.txt by following the instructions in paper.txt