Fix Checkstyle

src/main/java/seedu/waddle/commons/core/Messages.java

@@ -17,8 +17,8 @@ public class Messages {
     public static final String MESSAGE_CONFLICTING_ITEMS = "Quack, there is a time clash!"
             + "\nThe provided time clashes with:\n%1$sPlease change the start time and/or the duration.";
     public static final String MESSAGE_ITEM_PAST_MIDNIGHT =
-            "%1$s extends past midnight which is not currently supported.\n" +
-                    "Please split %1$s into 2 parts and plan the second part at the start of the next day.";
+            "%1$s extends past midnight which is not currently supported.\n"
+                    + "Please split %1$s into 2 parts and plan the second part at the start of the next day.";
     // not meant for users to see
     public static final String MESSAGE_UNKNOWN_STAGE = "Unknown stage, something went wrong with the StateManager.";
 }

src/main/java/seedu/waddle/model/item/exceptions/Period.java

@@ -1,20 +1,19 @@
 package seedu.waddle.model.item.exceptions;
 
-import java.time.LocalDate;
 import java.time.LocalTime;
 
 /**
  * This class encapsulates a time period.
  */
 public class Period {
-    private LocalTime start;
-    private LocalTime end;
+    private final LocalTime start;
+    private final LocalTime end;
 
     /**
      * Constructor.
      *
      * @param start Start time.
-     * @param end End time.
+     * @param end   End time.
      */
     public Period(LocalTime start, LocalTime end) {
         //assert(end.isAfter(start) || start.equals(end)) : "start and end time must be valid";