code: public static Integer getIntegerProperty(final ServiceReference<?> serviceReference, final String key) {
  		NullArgumentException.validateNotNull(serviceReference, "Service reference");
  		NullArgumentException.validateNotEmpty(key, true, "Property key");
  		final Object value = serviceReference.getProperty(key);
  		if (value instanceof Integer) {
  			return (Integer) value;
  		} else if (value != null) {
  			try {
  				return Integer.parseInt(String.valueOf(value));
  			} catch (NumberFormatException e) {
  				final String message = String.format("Property [%s] value must be an Integer: %s", key, e.getMessage());
  				LOG.error(message, e);
  				return null;
  			}
  		} else {
  			return null;
  		}
  	}
docs: Returns a property as Integer.
  
  @param serviceReference service reference; cannot be null
  @param key              property key; cannot be null
  @return property value; null if property is not set or property value is
  not an Integer
  @throws NullArgumentException - If service reference is null - If key is null