Adds coverage for free busy class (#137)

Adds coverage for free busy class

Author: RicardoGeek

src/test/java/com/nylas/FreeBusyTest.java

@@ -0,0 +1,42 @@
+package com.nylas;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.time.Instant;
+import java.util.LinkedList;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class FreeBusyTest {
+    private FreeBusy freeBusy;
+
+    @BeforeEach
+    public void init() throws NoSuchFieldException, IllegalAccessException {
+        freeBusy = new FreeBusy();
+
+        TimeSlot timeSlot = new TimeSlot();
+        timeSlot.setStartTime(Instant.ofEpochSecond(1670945645L));
+        timeSlot.setEndTime(Instant.ofEpochSecond(1670945645L));
+
+        List<TimeSlot> timeSlots = new LinkedList<>();
+        timeSlots.add(timeSlot);
+
+        FieldReflectionUtils.setField("email", "jdoe@gmail.com", freeBusy);
+        FieldReflectionUtils.setField("time_slots", timeSlots, freeBusy);
+    }
+
+    @Test
+    public void testGetters() {
+        assertEquals(freeBusy.getEmail(), "jdoe@gmail.com");
+        assertEquals(freeBusy.getTimeSlots().size(), 1);
+        assertEquals(freeBusy.getTimeSlots().get(0).getStartTime(), Instant.ofEpochSecond(1670945645L));
+        assertEquals(freeBusy.getTimeSlots().get(0).getEndTime(), Instant.ofEpochSecond(1670945645L));
+    }
+
+    @Test
+    public void testToString() {
+        assertEquals(freeBusy.toString(), "FreeBusy [email=jdoe@gmail.com, time_slots=[TimeSlot [status=null, start_time=2022-12-13T15:34:05Z, end_time=2022-12-13T15:34:05Z, emails=[]]]]");
+    }
+}