putLastName method
put Last Name
@param lastName String @return traits RudderTraits
Implementation
RudderTraits putLastName(String lastName) {
  __traitsMap["lastName"] = lastName;
  return this;
}put Last Name
@param lastName String @return traits RudderTraits
RudderTraits putLastName(String lastName) {
  __traitsMap["lastName"] = lastName;
  return this;
}