minLength (value, schema, opts) {
    return minLengthCommon('minLength', value, schema, opts)
  }
Validates the length of the provided string against a minimum value defined in the Schema's `minLength` keyword.
Validation succeeds if the length of the string is greater than, or equal to the value of this keyword.
see http://json-schema.org/latest/json-schema-validation.html#anchor29

@name Schema.validationKeywords.minLength
@method
@param {*} value String to be validated.
@param {object} schema Schema containing the `minLength` keyword.
@param {object} [opts] Configuration options.
@returns {(array|undefined)} Array of errors or `undefined` if valid.