Add support of -Yexplicit-nulls compiler option

[plokhotnyuk]

Macros that derive jsoniter-scala codecs encourage using non-null values, but generated codecs don't compiler validation with -Yexplicit-nulls.

Currently, workaround is using import scala.language.unsafeNulls in scopes of make macro calls, here:

given codec: JsonValueCodec[User] = {
  import scala.language.unsafeNulls

  JsonCodecMaker.make
}

[plokhotnyuk]

@lolgab @mohe2015 A partial support of -Yexplicit-nulls compiler option was added in v2.21.0

Now it should work for all supported types except Array and ArraySeq.

[mohe2015]

@lolgab @mohe2015 A partial support of -Yexplicit-nulls compiler option was added in v2.21.0

Now it should work for all supported types except Array and ArraySeq.

This is pretty nice! Seems like it also has issues with BigDecimal

[error] -- [E007] Type Mismatch Error: /home/moritz/Documents/reform/shared/src/main/scala/webapp/entity/SalaryChange.scala:44:71 
[error]  44 |  implicit val codec2: JsonValueCodec[BigDecimal] = JsonCodecMaker.make(CodecMakerConfig.withMapAsArray(true))
[error]     |                                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[error]     |Found:    (java.math.MathContext.DECIMAL128 : java.math.MathContext | Null)
[error]     |Required: java.math.MathContext
[error]     |
[error]     |The following import might make progress towards fixing the problem:
[error]     |
[error]     |  import sourcecode.Text.generate
[error]     |
[error]     |---------------------------------------------------------------------------
[error]     |Inline stack trace
[error]     |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
[error]     |This location contains code that was inlined from JsonCodecMaker.scala:824
[error]     |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
[error]     |This location contains code that was inlined from JsonCodecMaker.scala:824
[error]      ---------------------------------------------------------------------------
[error]     |
[error]     | longer explanation available when compiling with `-explain`
[error] one error found

[plokhotnyuk]

@mohe2015 Please check if v2.22.1 works for you

[mohe2015]

@mohe2015 Please check if v2.22.1 works for you

Yes, looking good, thank you very much!