NLPClient.kt

    private val pipeline: StanfordCoreNLP
        ...
    fun extractRootNoun(text: CharSequence): String? {
        val input = text.toString()
        val document = Annotation(input)
        pipeline.annotate(document)
        
        // Get split sentences
        val sentences: List<CoreMap> = document.get(CoreAnnotations.SentencesAnnotation::class.java)
        // Get the tokens for the sentences
        sentences.flatMap { sentence ->
            sentence.get(CoreAnnotations.TokensAnnotation::class.java)
        }.forEach { token ->
            // Get the text of each token
            val word = token.get(CoreAnnotations.TextAnnotation::class.java)
            // Get the corresponding POS tag of the token
            val pos = token.get(CoreAnnotations.PartOfSpeechAnnotation::class.java)

            //  Check if the POS tag is matched to a noun
            val partOfSpeechTag = pos.toString()
            if(partOfSpeechTag == "NN" || partOfSpeechTag == "NNS") {
                  // We found it, but we want the root form of the token which is the lemma
                    val lemmatizedValue = token.lemma().toString()
                    return lemmatizedValue
            }
        }
        return null
    }