My concateneate in groovy dont work

I have a question, how i can concateneate my way with my file

import java.util.Properties
def groovyUtils = new com.eviware.soapui.support.GroovyUtils(context)
def path = groovyUtils.projectPath



Properties properties = new Properties();
File propertiesFile = (path + JsonConfig.properties);
log.info propertiesFile
propertiesFile.withInputStream {
   stream -> properties.load(stream);
}

iterator = properties.keySet().iterator();

while(iterator.hasNext()) {
       key = iterator.next();
       value = properties[key];

       testRunner.testCase.testSuite.project.setPropertyValue(key, value);
}

Error

org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast object 'E:\JsonConfig.properties' with class 'java.lang.String' to class 'java.io.File' error at line: 9