Move unescapeBackslashes to a deprecated feature

api/src/org/labkey/api/reader/TabLoader.java

@@ -30,6 +30,7 @@
 import org.labkey.api.dataiterator.HashDataIterator;
 import org.labkey.api.iterator.BeanIterator;
 import org.labkey.api.iterator.CloseableIterator;
+import org.labkey.api.settings.AppProps;
 import org.labkey.api.util.FileType;
 import org.labkey.api.util.FileUtil;
 import org.labkey.api.util.JunitUtil;
@@ -67,6 +68,8 @@
  */
 public class TabLoader extends DataLoader
 {
+    public static final String FEATUREFLAG_UNESCAPE_BACKSLASH  = "dataloader-unescape-backslashes";
+
     public static final FileType TSV_FILE_TYPE = new TabFileType(Arrays.asList(".tsv", ".txt"), ".tsv", "text/tab-separated-values");
     public static final FileType CSV_FILE_TYPE = new TabFileType(Collections.singletonList(".csv"), ".csv", "text/comma-separated-values");
 
@@ -200,7 +203,7 @@ public FileType getFileType()
 
     private boolean _parseQuotes = true;
     private boolean _parseEnclosedQuotes = false; // only treat quote as quote if it comes in pairs, otherwise treat it as a regular character
-    private boolean _unescapeBackslashes = true;
+    private boolean _unescapeBackslashes = AppProps.getInstance().isOptionalFeatureEnabled(FEATUREFLAG_UNESCAPE_BACKSLASH);
 
     // Infer whether there are headers
     public TabLoader(File inputFile)

core/src/org/labkey/core/CoreModule.java

@@ -543,6 +543,11 @@ public QuerySchema createSchema(DefaultSchema schema, Module module)
             "Resolve Missing Lookup Values to Null",
             "When Lookup Validation for a field is not selected and lookup by alternate key is enabled, resolves missing lookup values to null instead of throwing an error. This option will be removed in LabKey Server v25.11.",
             false, false, OptionalFeatureService.FeatureType.Deprecated));
+        OptionalFeatureService.get().addFeatureFlag(new OptionalFeatureFlag(TabLoader.FEATUREFLAG_UNESCAPE_BACKSLASH,
+                "Unescape backslash character on import",
+                "Treat backslash '\\' character as an escape character when loading data from file.",
+                false, false, OptionalFeatureService.FeatureType.Deprecated));
+
 
         SiteValidationService svc = SiteValidationService.get();
         if (null != svc)

study/test/src/org/labkey/test/tests/study/StudyDatasetFileFieldTest.java

@@ -243,7 +243,7 @@ public void testFileField() throws IOException, CommandException
 
     private void importFilePathError(String participantId, String sequenceNum, String filePath)
     {
-        String pasteData = TestDataUtils.tsvStringFromRowMapsEscapeBackslash(List.of(
+        String pasteData = TestDataUtils.tsvStringFromRowMaps(List.of(
                 Map.of("ParticipantId", participantId, "SequenceNum", sequenceNum, FILE_FIELD_1, filePath)),
                 List.of("ParticipantId", "SequenceNum", FILE_FIELD_1), true);
         setFormElement(Locator.name("text"), pasteData);