code: public static Schema jointSchema(Schema leftSchema, Schema rightSchema) {
  		return jointSchema("jointSchema" + (COUNTER++), leftSchema, rightSchema);
  	}
docs: Creates a joint schema between two Schemas. All Fields from both schema are deduplicated
  and combined into a single Schema. The left Schema has priority so if both Schemas have
  the same Field with the same name but different Types, the Type from the left Schema will be
  taken.
  <p>
  The name of the schema is auto-generated with a static counter.