ClassCastException - getProperty() used with array

package soapui.testStep;

import java.util.List;

import com.eviware.soapui.model.testsuite.TestRunContext;
import com.eviware.soapui.model.testsuite.TestRunListener;
import com.eviware.soapui.model.testsuite.TestRunner;
import com.eviware.soapui.model.testsuite.TestStepResult;
import com.eviware.soapui.model.testsuite.TestStepResult.TestStepStatus;

public class TestStepListener implements TestRunListener {
    public void beforeRun(TestRunner testRunner, TestRunContext runContext) { }

    public void afterRun(TestRunner testRunner, TestRunContext runContext) { }

    public void beforeStep(TestRunner testRunner, TestRunContext runContext) { }

    public void afterStep(TestRunner testRunner, TestRunContext runContext, TestStepResult result) {
        if (result.getStatus()==TestStepStatus.FAILED) {
//            List sides = (List) runContext.getProperty("sides");
            String senderSideStatus, receiverSideStatus;

//            senderSideStatus   = (String) runContext.getProperty("expected" + (String) sides.get(0) + "ModelStatus");
//            receiverSideStatus = (String) runContext.getProperty("expected" + (String) sides.get(1) + "ModelStatus");
            senderSideStatus   = (String) runContext.getProperty("expected" + (String) runContext.getProperty("side0") + "ModelStatus");
            receiverSideStatus = (String) runContext.getProperty("expected" + (String) runContext.getProperty("side1") + "ModelStatus");


            if (runContext.getCurrentStep().getName().equals("receiveRequest") && (senderSideStatus.equals("Failed") || (senderSideStatus.equals("Started") && receiverSideStatus.equals("Failed")))) {
                // Test must fail so it is OK
            } else {
                runContext.setProperty("testFailed", true);
                runContext.setProperty("testStepName", runContext.getCurrentStep().getName());
                runContext.setProperty("testStepErrors", testRunner.getResults().get(runContext.getCurrentStepIndex()).getMessages());
            }

            testRunner.gotoStepByName("Loop to next properties file");
        }
    }
}