@SuppressWarnings("unchecked")
    public <K, V> Map<K, V> getMap(String fieldName) {
        return (Map<K, V>) getCheckType(fieldName, Schema.Type.MAP);
    }
Equivalent to calling {@link #get(String)} and casting the result to a Map.
connect/api/src/main/java/org/apache/kafka/connect/data/Struct.java