I am creating a simple plug-in to generate Fibonacci series. In my java code I h

my function appear in the expression rule. My java code for fibonacci series plugin is:

import java.util.ArrayList;

import org.apache.log4j.Logger;

import com.appiancorp.services.ServiceContext;
import com.appiancorp.suiteapi.expression.annotations.Function;
import com.appiancorp.suiteapi.expression.annotations.Parameter;
import com.appiancorp.suiteapi.type.AppianType;


@MathfunctionCategory
public class fibonacci {

          private static final Logger LOG = Logger.getLogger(fibonacci.class);

          @SuppressWarnings("deprecation")
          @Function(returnType=AppianType.ARRAY)
          public Integer[] fibonacci(ServiceContext sc, @Parameter(type=AppianType.INTEGER) int fibo) {
                    ArrayList<Integer> a = new ArrayList<Integer>();
                    int a0=0, a1=1;
                    a.add(a0);
                    a.add(a1);
                    int a2=0;
                    for(int i=2;i<fibo;i++)
                    {
                              a2=a0+a1;
                              a.add(a2);
                              a0=a1;
                              a1=a2;
                    }
                    
                    return (Integer[]) a.toArray();
          }

}

I get the error:

Expression evaluation error : Unresolved compilation problem: Type mismatch: cannot convert from Object[] to Integer[]

I am not sure why you reply to a 6 years old post, but find the documentation here:

docs.appian.com/.../extending-appian.html