in java/avro-converter/src/main/java/com/microsoft/azure/schemaregistry/kafka/connect/avro/AvroConverterUtils.java [1375:1379]
private static boolean isFixedSchema(Schema schema) {
return schema.type() == Schema.Type.BYTES && schema.name() != null
&& schema.parameters() != null
&& schema.parameters().containsKey(CONNECT_AVRO_FIXED_SIZE_PROP);
}