Replace SimpleDateFormat with DateTimeFormatter

Replace usages of the non-thread-safe date formatter with java.time's DateTimeFormatter and related APIs to improve thread-safety and correctness when parsing/formatting dates and time zones. Update calendar parameter conversion to use ZonedDateTime/Instant and adapt log timestamp formatting to use DateTimeFormatter.
Removes unused imports and modernizes date handling to avoid concurrency issues introduced by SimpleDateFormat.
Collectively decided to use `DateTimeFormatter` instead of `FastDateTime`.
Signed-off-by: Nico Piel <nico.piel@hotmail.de>

Author: NicoPiel

server/src/com/mirth/connect/client/core/api/providers/CalendarParamConverterProvider.java

@@ -9,23 +9,24 @@
 
 packagecom.mirth.connect.client.core.api.providers;
 
-importjava.lang.annotation.Annotation;
-importjava.lang.reflect.Type;
-importjava.text.ParseException;
-importjava.text.SimpleDateFormat;
-importjava.util.Calendar;
-
 importjavax.inject.Singleton;
 importjavax.ws.rs.ProcessingException;
 importjavax.ws.rs.ext.ParamConverter;
 importjavax.ws.rs.ext.ParamConverterProvider;
 importjavax.ws.rs.ext.Provider;
+importjava.lang.annotation.Annotation;
+importjava.lang.reflect.Type;
+importjava.time.Instant;
+importjava.time.ZoneId;
+importjava.time.ZonedDateTime;
+importjava.time.format.DateTimeFormatter;
+importjava.time.format.DateTimeParseException;
+importjava.util.Calendar;
 
 @Provider
 @Singleton
 publicclassCalendarParamConverterProviderimplementsParamConverterProvider {
-
-privatestaticfinalSimpleDateFormatformat = newSimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ");
+privatestaticfinalDateTimeFormatterFORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSZ");
 
 @Override
 public <T> ParamConverter<T> getConverter(Class<T> rawType, TypegenericType, Annotation[] annotations) {
@@ -38,10 +39,16 @@ public T fromString(String value) {
  }
 
 try {
-Calendardate = Calendar.getInstance();
-date.setTime(format.parse(value));
-return (T) date;
- } catch (ParseExceptione) {
+// Parse the incoming string as a ZonedDateTime using the given pattern
+ZonedDateTimezdt = ZonedDateTime.parse(value, FORMATTER);
+
+Calendarcalendar = Calendar.getInstance(java.util.TimeZone.getTimeZone(zdt.getZone()));
+calendar.setTimeInMillis(zdt.toInstant().toEpochMilli());
+
+@SuppressWarnings("unchecked")
+Tresult = (T) calendar;
+returnresult;
+ } catch (DateTimeParseExceptione) {
 thrownewProcessingException(e);
  }
  }
@@ -51,7 +58,15 @@ public String toString(T value) {
 if (value == null) {
 returnnull;
  }
-returnformat.format(((Calendar) value).getTime());
+
+Calendarcalendar = (Calendar) value;
+
+// Build a ZonedDateTime from the Calendar (date/time + time zone)
+Instantinstant = calendar.toInstant();
+ZoneIdzoneId = calendar.getTimeZone().toZoneId();
+ZonedDateTimezdt = ZonedDateTime.ofInstant(instant, zoneId);
+
+returnFORMATTER.format(zdt);
  }
  };
  }

server/src/com/mirth/connect/plugins/serverlog/ServerLogItem.java

@@ -10,14 +10,16 @@
 packagecom.mirth.connect.plugins.serverlog;
 
 importjava.io.Serializable;
-importjava.text.SimpleDateFormat;
+
+importjava.time.ZoneId;
+importjava.time.format.DateTimeFormatter;
 importjava.util.Date;
 
 importorg.apache.commons.lang3.StringUtils;
 
 publicclassServerLogItemimplementsSerializable {
 
-publicstaticSimpleDateFormatDATE_FORMAT = newSimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
+publicstaticDateTimeFormatterDATE_FORMAT = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS").withZone(ZoneId.systemDefault());
 
 privateStringserverId;
 privateLongid;
@@ -123,7 +125,7 @@ public void setThrowableInformation(String throwableInformation) {
 publicStringtoString() {
 if (id != null) {
 StringBuilderbuilder = newStringBuilder();
-builder.append('[').append(DATE_FORMAT.format(date)).append("] ");
+builder.append('[').append(DATE_FORMAT.format(date.toInstant())).append("] ");
 builder.append(level);
 builder.append(" (").append(category);
 if (StringUtils.isNotBlank(lineNumber)) {