controller endpoint to train sentiment model

train.java

@PostMapping("/sentiment/train")
public String train(@RequestBody List<TextData> data) throws IOException {
    Instant start = Instant.now();
    Dataset<Row> input = spark.createDataFrame(data, TextData.class);
    LOG.debug("Running training with {} rows of text data", data.size());
    Pipeline pipeline = getSentimentTrainingPipeline();
    PipelineModel newPipelineModel = pipeline.fit(input);
    long trainingTime = Duration.between(start, Instant.now()).toMillis();
    //Overwrite the existing scoring pipeline
    scoringPipeline = new LightPipeline(newPipelineModel, false);
    return String.format("Training completed in %s milliseconds", trainingTime);
}