unnecessary_string_interpolations
Unnecessary use of string interpolation.
Description
#The analyzer produces this diagnostic when a string literal contains a
single interpolation of a String-valued variable and no other
characters.
Example
#The following code produces this diagnostic because the string literal contains a single interpolation and doesn't contain any character outside the interpolation:
dart
String f(String s) => '$s';Common fixes
#Replace the string literal with the content of the interpolation:
dart
String f(String s) => s;