Schema Converter for getting schema in json format into a spark Structure

The given schema for spark has almost no validity checks, so it will make sense to combine this with the schema-validator. For loading data with schema, data is converted to the type given in the schema. If this is not possible the whole row will be null (!). A field can be null if its type is a 2-element array, one of which is "null". The converted schema doesn't check for 'enum' fields, i.e. fields which are limited to a given set. It also doesn't check for required fields or if additional properties are set to true or false. If a field is specified in the schema, than you can select it and it will be null if missing. If a field is not in the schema, it cannot be selected even if given in the dataset.