code: public String getCommonProperty(String key, String defaultValue) {
  		return props.getProperty(PropertiesBundleConstant.PROPS_PREFIX + key, defaultValue);
  	}
docs: Returns the value of the common property, or the default value if no
  value is defined instead.
  
  @param key
  the key of the property
  @param defaultValue
  the default value
  @return the value of the common property