remove the minInterfaces feature flag in TransactionVersion (#18446)

daml-lf/transaction-test-lib/src/main/scala/lf/value/test/ValueGenerators.scala

@@ -29,8 +29,6 @@ import scalaz.scalacheck.ScalaCheckBinding._
 
 object ValueGenerators {
 
-  import TransactionVersion.minInterfaces
-
   // generate decimal values
   def numGen(scale: Numeric.Scale): Gen[Numeric] = {
     val num = for {
@@ -377,7 +375,7 @@ object ValueGenerators {
       targetCoid <- coidGen
       pkgName <- pkgNameGen(version)
       templateId <- idGen
-      interfaceId <- if (version < minInterfaces) Gen.const(None) else Gen.option(idGen)
+      interfaceId <- Gen.option(idGen)
       choiceId <- nameGen
       consume <- Gen.oneOf(true, false)
       actingParties <- genNonEmptyParties

daml-lf/transaction/src/main/scala/com/digitalasset/daml/lf/transaction/TransactionCoder.scala

@@ -301,11 +301,9 @@ object TransactionCoder {
               if (nodeVersion >= TransactionVersion.minByKey) {
                 discard(builder.setByKey(ne.byKey))
               }
-              if (nodeVersion >= TransactionVersion.minInterfaces) {
-                ne.interfaceId.foreach(iface =>
-                  builder.setInterfaceId(ValueCoder.encodeIdentifier(iface))
-                )
-              }
+              ne.interfaceId.foreach(iface =>
+                builder.setInterfaceId(ValueCoder.encodeIdentifier(iface))
+              )
               for {
                 encodedPkgName <- encodePackageName(ne.packageName, nodeVersion)
                 _ = builder.setPackageName(encodedPkgName)
@@ -552,7 +550,7 @@ object TransactionCoder {
               protoExe.getByKey
             else false
           interfaceId <-
-            if (nodeVersion >= TransactionVersion.minInterfaces && protoExe.hasInterfaceId) {
+            if (protoExe.hasInterfaceId) {
               ValueCoder.decodeIdentifier(protoExe.getInterfaceId).map(Some(_))
             } else {
               Right(None)

daml-lf/transaction/src/main/scala/com/digitalasset/daml/lf/transaction/TransactionVersion.scala

@@ -48,10 +48,8 @@ object TransactionVersion {
   val minVersion: TransactionVersion = All.min
   def maxVersion: TransactionVersion = VDev
 
-  // TODO(https://github.com/digital-asset/daml/issues/18240) remove these 3 feature flags and kill
-  //  the transitively dead code. Make sure canton doesn't mention them anymore.
+  // TODO(https://github.com/digital-asset/daml/issues/18240) move this feature flag to VDev.
   private[lf] val minByKey = V14
-  private[lf] val minInterfaces = V15
 
   private[lf] val minUpgrade = V31
   private[lf] val minSharedKeys = V31

daml-lf/transaction/src/test/scala/com/digitalasset/daml/lf/transaction/TransactionCoderSpec.scala

@@ -1115,10 +1115,7 @@ class TransactionCoderSpec
       case _ => exe
     }
     node.copy(
-      interfaceId =
-        if (exe.version >= TransactionVersion.minInterfaces)
-          exe.interfaceId
-        else None,
+      interfaceId = exe.interfaceId,
       chosenValue = normalize(exe.chosenValue, exe.version),
       exerciseResult = exe.exerciseResult.map(normalize(_, exe.version)),
       choiceObservers = exe.choiceObservers,