Handle null values in IntervalConverter and TimestampConverter in jOOQ (#190)

Author: Daza10samu

jooq-dialect/src/main/java/tech/ydb/jooq/binding/Interval64Binding.java

@@ -44,12 +44,12 @@ private static class IntervalConverter implements Converter<ULong, Duration> {
 
         @Override
         public Duration from(ULong databaseObject) {
-            return Duration.of(databaseObject.longValue(), ChronoUnit.MICROS);
+            return databaseObject == null ? null : Duration.of(databaseObject.longValue(), ChronoUnit.MICROS);
         }
 
         @Override
         public ULong to(Duration userObject) {
-            return ULong.valueOf(TimeUnit.NANOSECONDS.toMicros(userObject.toNanos()));
+            return userObject == null ? null : ULong.valueOf(TimeUnit.NANOSECONDS.toMicros(userObject.toNanos()));
         }
 
         @Override

jooq-dialect/src/main/java/tech/ydb/jooq/binding/IntervalBinding.java

@@ -39,12 +39,12 @@ public void get(BindingGetResultSetContext<Duration> ctx) throws SQLException {
     private static class IntervalConverter implements Converter<YearToSecond, Duration> {
         @Override
         public Duration from(YearToSecond databaseObject) {
-            return databaseObject.toDuration();
+            return databaseObject == null ? null : databaseObject.toDuration();
         }
 
         @Override
         public YearToSecond to(Duration userObject) {
-            return YearToSecond.valueOf(userObject);
+            return userObject == null ? null : YearToSecond.valueOf(userObject);
         }
 
         @Override

jooq-dialect/src/main/java/tech/ydb/jooq/binding/TimestampBinding.java

@@ -39,12 +39,12 @@ public void get(BindingGetResultSetContext<Instant> ctx) throws SQLException {
     private static class TimestampConverter implements Converter<LocalDateTime, Instant> {
         @Override
         public Instant from(LocalDateTime databaseObject) {
-            return databaseObject.toInstant(ZoneOffset.UTC);
+            return databaseObject == null ? null : databaseObject.toInstant(ZoneOffset.UTC);
         }
 
         @Override
         public LocalDateTime to(Instant userObject) {
-            return LocalDateTime.ofInstant(userObject, ZoneOffset.UTC);
+            return userObject == null ? null : LocalDateTime.ofInstant(userObject, ZoneOffset.UTC);
         }
 
         @Override

jooq-dialect/src/main/java/tech/ydb/jooq/binding/YsonBinding.java

@@ -39,7 +39,7 @@ public void get(BindingGetResultSetContext<YSON> ctx) throws SQLException {
     private static class YsonConverter implements Converter<Object, YSON> {
         @Override
         public YSON from(Object databaseObject) {
-            return (YSON) databaseObject;
+            return databaseObject == null ? null : (YSON) databaseObject;
         }
 
         @Override