I coded indicator which use CSS (CurrencySlopeStrength indicator).
I want get array of double[8] and make some calculation with this.
My code give null pointer exception - in log file error is outside my indicator - in CSS indicator code:
context.getFeedDescriptor() == null.

I probably wrong initialize CSS indicator. Can you help me with this?

This is my code:

package jforex3;

import com.dukascopy.api.IBar;
import com.dukascopy.api.IConsole;
import com.dukascopy.api.indicators.*;

public class paramCSSind implements IIndicator {

    private IIndicatorContext context;
    private IConsole console;
    private IIndicator css;
    
    private IndicatorInfo indicatorInfo;
    private InputParameterInfo[] inputParameterInfos;
    private OptInputParameterInfo[] optInputParameterInfos;
    private OutputParameterInfo[] outputParameterInfos;
    
    private IBar[][] inputs = new IBar[1][];
    private double[][] outputs = new double[1][];
    private double[][] outCSS;
    
    int inpNr, inpOptNr, outNr;

public void onStart(IIndicatorContext context) {
        this.context = context;        
        this.console = context.getConsole();
        IIndicatorsProvider indicatorsProvider = context.getIndicatorsProvider();
        css = indicatorsProvider.getIndicator("CSS");

        IndicatorInfo infoCSS = css.getIndicatorInfo();
        inpNr = infoCSS.getNumberOfInputs();
        inpOptNr = infoCSS.getNumberOfOptionalInputs();
        outNr = infoCSS.getNumberOfOutputs();

        indicatorInfo = new IndicatorInfo("paramCSSind", "raw CSS for pair", "My indicators",
                false, false, false, 1, 0, 1);

        inputParameterInfos = new InputParameterInfo[] {
            new InputParameterInfo("Bars", InputParameterInfo.Type.BAR)
        };

        outputParameterInfos = new OutputParameterInfo[] {
            new OutputParameterInfo("out", OutputParameterInfo.Type.DOUBLE,
                OutputParameterInfo.DrawingStyle.LINE)
        };
    }
    public IndicatorResult calculate(int startIndex, int endIndex) {
        //calculating startIndex taking into account lookback value
        if (startIndex - getLookback() < 0) {
            startIndex = getLookback();
        }
        if (startIndex > endIndex) {
            return new IndicatorResult(0, 0);
        }
        css.setInputParameter(0, inputs[0]);
        double[][] outCSS = new double[outNr][endIndex - startIndex + 1];
        for (int i = 0; i < outNr; i++) {
            css.setOutputParameter(i, outCSS[i]);
        }
        console.getOut().format("%d %d %d %d %d %d \n", startIndex, endIndex, inputs.length, inputs[0].length, outCSS.length, outCSS[0].length  );
        css.calculate(0, inputs[0].length -1 );
        int i, j;       
        for (i = startIndex, j = 0; i <= endIndex; i++, j++) {
            outputs[0][j] = outCSS[0][j];
            console.getOut().format("%.3f ", outCSS[0][j] );
        }
        console.getOut().println();
        return new IndicatorResult(startIndex, j);
    }

    public IndicatorInfo getIndicatorInfo() {
        return indicatorInfo;
    }

    public InputParameterInfo getInputParameterInfo(int index) {
        if (index < inputParameterInfos.length) {
            return inputParameterInfos[index];
        }
        return null;
    }

    public int getLookback() {
        return 0;
    }

    public int getLookforward() {
        return 0;
    }

    public OptInputParameterInfo getOptInputParameterInfo(int index) {
        if (index < optInputParameterInfos.length) {
            return optInputParameterInfos[index];
        }
        return null;
    }

    public OutputParameterInfo getOutputParameterInfo(int index) {
        if (index < outputParameterInfos.length) {
            return outputParameterInfos[index];
        }
        return null;
    }

    public void setInputParameter(int index, Object array) {
        inputs[index] = (IBar[]) array;
    }

    public void setOptInputParameter(int index, Object value) {
    }

    public void setOutputParameter(int index, Object array) {
        outputs[index] = (double[]) array;
    }
    
   }

Error in lines:

// my indicator
css.calculate(0, inputs[0].length -1 );

// css indicator
DataType dataType = context.getFeedDescriptor().getDataType();