@Internal
    @Override
    public SourceReader<OUT, PulsarPartitionSplit> createReader(SourceReaderContext readerContext)
            throws Exception {
        // Initialize the deserialization schema before creating the pulsar reader.
        PulsarDeserializationSchemaInitializationContext initializationContext =
                new PulsarDeserializationSchemaInitializationContext(readerContext);
        deserializationSchema.open(initializationContext, sourceConfiguration);

        return PulsarSourceReaderFactory.create(
                readerContext, deserializationSchema, sourceConfiguration, enableLogReport);
    }
Get a PulsarSourceBuilder to builder a {@link PulsarSource}.

@return a Pulsar source builder.
inlong-sort/sort-flink/sort-flink-v1.15/sort-connectors/pulsar/src/main/java/org/apache/inlong/sort/pulsar/source/PulsarSource.java