change identifier index

now users can begin counting at 1 for the identifier column instead
of 0. this makes it consistent with the header line index.

src/main/kotlin/KafkaTopology.kt

@@ -140,7 +140,8 @@ class KafkaTopology(private val settings: SettingsLoader) {
                     }
                     continue
                 }
-                val identifier = line[identifierIndex]
+                // the +1 ensures, that users can start columns beginning at 1!
+                val identifier = line[identifierIndex + 1]
                 when {
                     identifier.isEmpty() -> {
                         throw InvalidInputException("The unique identifier in column $identifierIndex in row $count is empty!")

src/main/resources/app.yml

@@ -7,7 +7,7 @@ app:
   sheet: ${SHEET_INDEX:?user}
   header:
     count: ${HEADER_COUNT:?user}
-    line: ${USED_HEADER_LINE_INDEX:?user}
+    line: ${HEADER_LINE_INDEX:?user}
   identifier: ${IDENTIFIER_INDEX:?user}
 kafka:
   producer: