Check out example codes for "add retrofit dependency android". It will help you in understanding the concepts better.

Code Example 1

implementation 'com.squareup.retrofit2:retrofit:2.9.0'

Code Example 2

implementation 'com.squareup.retrofit2:retrofit:(insert latest version)'
Gson: com.squareup.retrofit2:converter-gson

Code Example 3

implementation 'com.squareup.retrofit2:retrofit:2.4.0'
implementation 'com.squareup.retrofit2:converter-gson:2.4.0'

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