Mongo document read with non hex objectid

I have a mongo collection which has non-hex '_id' in form a string.
I cant read them into a PCollection getting following exception
Exception in thread "main" java.lang.IllegalArgumentException: invalid hexadecimal representation of an ObjectId: [somestring]
at org.bson.types.ObjectId.parseHexString(ObjectId.java:523)
at org.bson.types.ObjectId.<init>(ObjectId.java:237)
at org.bson.json.JsonReader.visitObjectIdConstructor(JsonReader.java:674)
at org.bson.json.JsonReader.readBsonType(JsonReader.java:197)
at org.bson.codecs.DocumentCodec.decode(DocumentCodec.java:139)
at org.bson.codecs.DocumentCodec.decode(DocumentCodec.java:45)
at org.bson.codecs.configuration.LazyCodec.decode(LazyCodec.java:47)
at org.bson.codecs.DocumentCodec.readValue(DocumentCodec.java:215)
at org.bson.codecs.DocumentCodec.decode(DocumentCodec.java:141)
at org.bson.codecs.DocumentCodec.decode(DocumentCodec.java:45)
at org.bson.codecs.DocumentCodec.readValue(DocumentCodec.java:215)
at org.bson.codecs.DocumentCodec.readList(DocumentCodec.java:222)
at org.bson.codecs.DocumentCodec.readValue(DocumentCodec.java:208)
at org.bson.codecs.DocumentCodec.decode(DocumentCodec.java:141)
at org.bson.codecs.DocumentCodec.decode(DocumentCodec.java:45)
at org.bson.Document.parse(Document.java:105)
at org.bson.Document.parse(Document.java:90)
at org.apache.beam.sdk.io.mongodb.MongoDbIO$BoundedMongoDbReader.start(MongoDbIO.java:472)
at org.apache.beam.runners.direct.BoundedReadEvaluatorFactory$BoundedReadEvaluator.processElement(BoundedReadEvaluatorFactory.java:141)
at org.apache.beam.runners.direct.TransformExecutor.processElements(TransformExecutor.java:146)
at org.apache.beam.runners.direct.TransformExecutor.run(TransformExecutor.java:110)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:748)