getBootstrapColumnClass(className) {
    if (className) {
      const splitClasses = className.split(' ').filter(className => bootstrapColumnRegex.test(className))
      if (splitClasses && splitClasses.length > 0) {
        return splitClasses[0]
      }
    }
    return ''
  }
Return full class name (col-md-6)
@param {string} className
@returns {string}