Fix for issue causing tradeTimestamp to report as 0 for trades in archived blocks.

src/main/java/org/qortal/api/resource/CrossChainResource.java

@@ -222,6 +222,10 @@ public class CrossChainResource {
 
 					// We also need block timestamp for use as trade timestamp
 					long timestamp = repository.getBlockRepository().getTimestampFromHeight(atState.getHeight());
+					if (timestamp == 0) {
+						// Try the archive
+						timestamp = repository.getBlockArchiveRepository().getTimestampFromHeight(atState.getHeight());
+					}
 
 					CrossChainTradeSummary crossChainTradeSummary = new CrossChainTradeSummary(crossChainTradeData, timestamp);
 					crossChainTrades.add(crossChainTradeSummary);

src/main/java/org/qortal/repository/BlockArchiveRepository.java

@@ -71,6 +71,15 @@ public interface BlockArchiveRepository {
      */
     public int getHeightFromTimestamp(long timestamp) throws DataException;
 
+    /**
+     * Returns block timestamp for a given height.
+     *
+     * @param height
+     * @return timestamp, or 0 if height is out of bounds.
+     * @throws DataException
+     */
+    public long getTimestampFromHeight(int height) throws DataException;
+
     /**
      * Returns block summaries for blocks signed by passed public key, or reward-share with minter with passed public key.
      */

src/main/java/org/qortal/repository/hsqldb/HSQLDBBlockArchiveRepository.java

@@ -103,6 +103,20 @@ public class HSQLDBBlockArchiveRepository implements BlockArchiveRepository {
         }
     }
 
+    @Override
+    public long getTimestampFromHeight(int height) throws DataException {
+        String sql = "SELECT minted_when FROM BlockArchive WHERE height = ?";
+
+        try (ResultSet resultSet = this.repository.checkedExecute(sql, height)) {
+            if (resultSet == null)
+                return 0;
+
+            return resultSet.getLong(1);
+        } catch (SQLException e) {
+            throw new DataException("Error obtaining block timestamp by height from BlockArchive repository", e);
+        }
+    }
+
     @Override
     public List<BlockSummaryData> getBlockSummariesBySigner(byte[] signerPublicKey, Integer limit, Integer offset, Boolean reverse) throws DataException {
         StringBuilder sql = new StringBuilder(512);