proficiency_hints property Null safety

1. baguette
2. i18n
3. I18n
4. proficiency_hints property

I18n class

1. Constructors
2. I18n
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Static properties
12. aa
13. archive
14. archives
15. baguette
16. bank_card_expire_empty
17. bank_card_form_cvv
18. bank_card_form_cvv_error
19. bank_card_form_cvv_hints
20. bank_card_form_expire
21. bank_card_form_expire_hints
22. bank_card_form_exprie_error
23. bank_card_form_holder
24. bank_card_form_holder_error
25. bank_card_form_holder_hints
26. bank_card_form_number
27. bank_card_form_number_error
28. bank_card_form_number_hints
29. bank_card_holder_empty
30. bank_card_number_empty
31. camera
32. cancel
33. checkout_security
34. congratulation
35. conversation
36. conversations
37. copy
38. country
39. country_hints
40. currency
41. currency_hints
42. currentLanguage
43. currentLocale
44. disable_from_settings
45. dots
46. enable_from_settings
47. environment
48. error
49. error_already_exists
50. error_camera_unavailable
51. error_crash_error_stack
52. error_invalid_information
53. error_localization_unavailable
54. error_no_connectivity
55. error_operation_cancel
56. error_require_authorization
57. friday
58. friday_short
59. gallery
60. language
61. language_hints
62. leavy
63. localization
64. media_error_load_fail
65. media_error_max_duration
66. media_error_min_duration
67. media_error_unknown_format
68. media_pick_photo
69. media_pick_video
70. media_take_photo
71. media_take_video
72. message
73. message_error
74. message_hints
75. message_write
76. messages
77. messenger
78. microphone
79. mode
80. mode_hints
81. monday
82. monday_short
83. na
84. no
85. not_available
86. notifications
87. now
88. ok
89. oops
90. proficency_fluent
91. proficiency
92. proficiency_advance
93. proficiency_elementary
94. proficiency_hints
95. proficiency_intermediate
96. proficiency_native
97. report
98. restart
99. restart_application_message
100. retry
101. saturday
102. saturday_short
103. save
104. search
105. settings
106. sorry
107. speech
108. storage
109. success
110. sunday
111. sunday_short
112. theme
113. theme_hints
114. thursday
115. thursday_short
116. today
117. tuesday
118. tuesday_short
119. unarchive
120. unknown
121. update
122. update_application_message
123. wednesday
124. wednesday_short
125. yay
126. yes
127. yesterday
128. Static methods
129. load