added Date / LocalDate conversion helper

util/src/main/java/de/muehlencord/shared/util/DateUtil.java

@@ -1,5 +1,8 @@
 package de.muehlencord.shared.util;
 
+import java.time.Instant;
+import java.time.LocalDate;
+import java.time.ZoneId;
 import java.time.ZoneOffset;
 import java.time.ZonedDateTime;
 import java.util.Date;
@@ -15,4 +18,18 @@ public class DateUtil {
         return Date.from(utc.toInstant());
     }
 
+    public static Date getDate(final LocalDate localDate) {
+        return Date.from(localDate.atStartOfDay(ZoneId.systemDefault()).toInstant());
+    }
+
+    public static LocalDate getDate(final Date date) {
+        if (date == null)
+            return null;
+        // ensure to call toInstant on java.util.Date and not on java.sql.Date because this will throw an UnsupportedOperationException 
+        // see Java doc of java.sql.Date.toInstant()
+        Instant instant = new java.util.Date(date.getTime()).toInstant();
+        ZonedDateTime zdt = instant.atZone(ZoneId.systemDefault());
+        return zdt.toLocalDate();
+    }
+
 }