code: public static boolean isStringSet(PrefsProperty property) {
  		boolean isStringSet = false;
  
  		TypeName typeName;
  		if (property.hasTypeAdapter()) {
  			typeName = TypeUtility.typeName(property.typeAdapter.dataType);
  		} else {
  			typeName = TypeUtility.typeName(property.getElement().asType());
  		}
  
  		// it is parameterized type name for sure
  
  		if (typeName instanceof ParameterizedTypeName && TypeUtility.isSet(typeName)) {
  			ParameterizedTypeName parameterizedTypeName = (ParameterizedTypeName) typeName;
  			if (TypeUtility.isEquals(parameterizedTypeName.typeArguments.get(0), String.class.getCanonicalName())) {
  				isStringSet = true;
  			}
  		}
  
  		return isStringSet;
  	}
docs: Checks if is string set.
  
  @param property the property
  @return true, if is string set