private String timestampTypeFromSchema(Schema schema) {
        if (Timestamp.LOGICAL_NAME.equals(schema.name())) {
            return TYPE_TIMESTAMP;
        } else if (org.apache.kafka.connect.data.Date.LOGICAL_NAME.equals(schema.name())) {
            return TYPE_DATE;
        } else if (Time.LOGICAL_NAME.equals(schema.name())) {
            return TYPE_TIME;
        } else if (schema.type().equals(Schema.Type.STRING)) {
            // If not otherwise specified, string == user-specified string format for timestamps
            return TYPE_STRING;
        } else if (schema.type().equals(Schema.Type.INT64)) {
            // If not otherwise specified, long == unix time
            return TYPE_UNIX;
        }
        throw new ConnectException("Schema " + schema + " does not correspond to a known timestamp type format");
    }
Determine the type/format of the timestamp based on the schema
connect/transforms/src/main/java/org/apache/kafka/connect/transforms/TimestampConverter.java