Mix schema record source creates corrupt record

This seems to be an unexpected side effect with how AvroDeserializationSchema class was written.

Sometimes we do not have control over what record comes through a Kafka Topic.

In current implementation, if AvroDeserializationSchema encountered a record byte array that does not conform to the specified Schema / SpecificRecord type, it will cause future record to be deserialized incorrectly.

Origin of the issue is with how

AvroDeserializationSchema.deserialize

handles exception, and how

AvroDeserializationSchema.checkAvroInitialized

handles initialization of Decoder object