[Bug]: Select Values conversion error

[mattcasters]

Apache Hop version?

2.18.0-SNAPSHOT

Java version?

OpenJDK 21

Operating system

Linux

What happened?

In a rare scenario when converting Strings to Timestamps (with ns precision) in 2 transform copies of the Select Values transform I get:

2026/04/27 09:44:48 [Error]    to timestamp.0 - Unexpected error
2026/04/27 09:44:48 [Error]    to timestamp.0 - org.apache.hop.core.exception.HopConversionException: 
2026/04/27 09:44:48 [Error]    to timestamp.0 - 
2026/04/27 09:44:48 [Error]    to timestamp.0 - Error converting value event_timestamp_str to type Timestamp with source value: [2025/03/03 10:01:19.899750000]
2026/04/27 09:44:48 [Error]    to timestamp.0 - Index 15 out of bounds for length 13
2026/04/27 09:44:48 [Error]    to timestamp.0 - 
2026/04/27 09:44:48 [Error]    to timestamp.0 - 
2026/04/27 09:44:48 [Error]    to timestamp.0 - 	at org.apache.hop.pipeline.transforms.selectvalues.SelectValues.metadataValues(SelectValues.java:390)
2026/04/27 09:44:48 [Error]    to timestamp.0 - 	at org.apache.hop.pipeline.transforms.selectvalues.SelectValues.processRow(SelectValues.java:439)
2026/04/27 09:44:48 [Error]    to timestamp.0 - 	at org.apache.hop.pipeline.transform.RunThread.run(RunThread.java:54)
2026/04/27 09:44:48 [Error]    to timestamp.0 - 	at java.base/java.lang.Thread.run(Thread.java:1583)

This is caused by the 2 copies (somehow!) using the same SimpleDateFormat object.

The situation occured when reading with a Text File Input transform with an epoch timestamp (2 copies), then building a String with JavaScript (2 copies) and then the Select Values (2 copies) with the error.

Issue Priority

Priority: 2

Issue Component

Component: Transforms

[mattcasters]

This is caused by the static final values in SimpleTimestampFormat.java:

private static final SimpleDateFormat defaultTimestampFormat =
      new SimpleDateFormat(DEFAULT_TIMESTAMP_FORMAT_FOR_TIMESTAMP, Locale.US);

  private static final SimpleDateFormat defaultMillisecondDateFormat =
      new SimpleDateFormat(DEFAULT_MILLISECOND_DATE_FORMAT, Locale.US);

These fields can NOT be static, making them shared between all instances of the class.