Update ParallelIndexIOConfig.inputFormat to be optional

Author: winsmith

Sources/DataTransferObjects/Druid/indexing/common/task/batch/parallel/ParallelIndexIOConfig.swift

@@ -1,15 +1,15 @@
 /// https://druid.apache.org/docs/latest/ingestion/native-batch#ioconfig
 /// https://github.com/apache/druid/blob/master/indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/parallel/ParallelIndexIOConfig.java
 public struct ParallelIndexIOConfig: Codable, Hashable, Equatable {
-    public init(inputFormat: InputFormat, inputSource: InputSource? = nil, appendToExisting: Bool? = nil, dropExisting: Bool? = nil) {
+    public init(inputFormat: InputFormat?, inputSource: InputSource? = nil, appendToExisting: Bool? = nil, dropExisting: Bool? = nil) {
         self.inputFormat = inputFormat
         self.inputSource = inputSource
         self.appendToExisting = appendToExisting
         self.dropExisting = dropExisting
     }
-    
+
     /// inputFormat to specify how to parse input data.
-    public let inputFormat: InputFormat
+    public let inputFormat: InputFormat?
 
     public let inputSource: InputSource?