@SuppressWarnings("unchecked")
    private <T extends OUT> PulsarSourceBuilder<T> specialized() {
        return (PulsarSourceBuilder<T>) this;
    }
Helper method for java compiler recognizes the generic type.
inlong-sort/sort-flink/sort-flink-v1.18/sort-connectors/pulsar/src/main/java/org/apache/inlong/sort/pulsar/source/PulsarSourceBuilder.java