Fix style errors

src/main/java/unicash/commons/util/Pair.java

@@ -5,7 +5,7 @@
  * @param <T> type parameter of the first type of {@code Object} to be contained
  * @param <U> type parameter of the second type of {@code Object} to be contained
  */
-public class Pair<T,U> {
+public class Pair<T, U> {
     private T t;
     private U u;
 

src/main/java/unicash/logic/parser/FilterCommandParser.java

@@ -9,12 +9,9 @@
 import static unicash.logic.parser.CliSyntax.PREFIX_NAME;
 import static unicash.logic.parser.CliSyntax.PREFIX_TYPE;
 
-import java.util.List;
-
 import unicash.logic.commands.FilterCommand;
 import unicash.logic.parser.exceptions.ParseException;
 import unicash.model.category.Category;
-import unicash.model.category.UniqueCategoryList;
 import unicash.model.commons.Amount;
 import unicash.model.transaction.DateTime;
 import unicash.model.transaction.Location;

src/main/java/unicash/model/transaction/predicates/BooleanPredicatePair.java

@@ -1,9 +1,10 @@
 package unicash.model.transaction.predicates;
 
+import java.util.function.Predicate;
+
 import unicash.commons.util.Pair;
 import unicash.model.transaction.Transaction;
 
-import java.util.function.Predicate;
 
 /**
  * A wrapper class for containing Boolean and TransactionPredicate pairs.

src/main/java/unicash/model/transaction/predicates/TransactionContainsAllKeywordsPredicate.java

@@ -24,7 +24,7 @@ public class TransactionContainsAllKeywordsPredicate
     public static final String EMPTY_STRING = "";
     public static final List<String> EMPTY_STRING_LIST = List.of(EMPTY_STRING);
 
-    public HashMap<TransactionProperty, BooleanPredicatePair>
+    private HashMap<TransactionProperty, BooleanPredicatePair>
             predicatePairMap = new HashMap<>();
 
     /**