Convert SQL Timestamp to Instant to allow custom formatters

Author: greek1979

Diff for: src/main/java/org/eclipse/yasson/internal/serializer/types/SqlTimestampSerializer.java

@@ -15,6 +15,7 @@
 import java.sql.Timestamp;
 import java.time.Instant;
 import java.time.format.DateTimeFormatter;
+import java.time.temporal.TemporalAccessor;
 import java.util.Locale;
 
 /**
@@ -31,6 +32,12 @@ class SqlTimestampSerializer extends AbstractDateSerializer<Timestamp> {
         super(serializerBuilder);
     }
 
+    @Override
+    protected TemporalAccessor toTemporalAccessor(Timestamp value) {
+    	// convert SQL Timestamp into an Instant so it can be cast to TemporalAccessor
+        return value.toInstant();
+    }
+
     @Override
     protected Instant toInstant(Timestamp value) {
         return value.toInstant();