Sentences Annotation Class giving null value using Stanford Core NLP using c#

Question

Below is my code running into console application in visual studio

using System;
using System.Collections.Generic;
using edu.stanford.nlp.ling;
using edu.stanford.nlp.pipeline;
using edu.stanford.nlp.util;
namespace ConsoleApp1
{
class Program
{
    readonly static java.lang.Class sentencesAnnotationClass =
    new CoreAnnotations.SentencesAnnotation().getClass();
    readonly static java.lang.Class tokensAnnotationClass =
        new CoreAnnotations.TokensAnnotation().getClass();
    readonly static java.lang.Class textAnnotationClass =
        new CoreAnnotations.TextAnnotation().getClass();
    readonly static java.lang.Class partOfSpeechAnnotationClass =
        new CoreAnnotations.PartOfSpeechAnnotation().getClass();
    readonly static java.lang.Class namedEntityTagAnnotationClass =
        new CoreAnnotations.NamedEntityTagAnnotation().getClass();
    readonly static java.lang.Class normalizedNamedEntityTagAnnotation =
        new CoreAnnotations.NormalizedNamedEntityTagAnnotation().getClass();

    static void Main(string[] args)
    {            
            // creates a StanfordCoreNLP object with POS tagging, lemmatization, NER, parsing, and coreference resolution
            var props = new java.util.Properties();
        props.setProperty("annotators", "tokenize, ssplit, pos, lemma, ner, parse, dcoref");
        props.setProperty("ner.useSUTime", "0");

        StanfordCoreNLPClient pipeline = new StanfordCoreNLPClient(props, "http://localhost", 9000, 2);
            // read some text in the text variable
            var text = "Kosgi Santosh sent an email to Stanford University.";
        // create an empty Annotation just with the given text
        Annotation document = new Annotation(text);
            // run all Annotators on this text
            pipeline.annotate(document);
        var sentences = document.get(sentencesAnnotationClass) as java.util.AbstractList;
        foreach (CoreMap sentence in sentences)
            {
                var tokens = sentence.get(tokensAnnotationClass) as java.util.AbstractList;
                Console.WriteLine("----");
                foreach (CoreLabel token in tokens)
                {
                    var word = token.get(textAnnotationClass);
                    var pos = token.get(partOfSpeechAnnotationClass);
                    var ner = token.get(namedEntityTagAnnotationClass);
                    Console.WriteLine("{0}\t[pos={1};\tner={2};", word, pos, ner);
                }
            }       
    }

     
}

}

In below screen short of highlighted line execution then getting null value.

I am trying since long time why this above line giving null value, actually my requirement is NER to involve into my project thats the reason executing this code.