code: func ValidateFieldManager(fieldManager string, fldPath *field.Path) field.ErrorList {
  	allErrs := field.ErrorList{}
  	// the field can not be set as a `*string`, so a empty string ("") is
  	// considered as not set and is defaulted by the rest of the process
  	// (unless apply is used, in which case it is required).
  	if len(fieldManager) > FieldManagerMaxLength {
  		allErrs = append(allErrs, field.TooLong(fldPath, fieldManager, FieldManagerMaxLength))
  	}
  	// Verify that all characters are printable.
  	for i, r := range fieldManager {
  		if !unicode.IsPrint(r) {
  			allErrs = append(allErrs, field.Invalid(fldPath, fieldManager, fmt.Sprintf("invalid character %#U (at position %d)", r, i)))
  		}
  	}
  
  	return allErrs
  }
docs: // ValidateFieldManager valides that the fieldManager is the proper length and
  // only has printable characters.