Fix unwanted trimming of whitespaces for backtiked field names in Scala 2 macros

Author: plokhotnyuk

jsoniter-scala-macros/shared/src/main/scala-2/com/github/plokhotnyuk/jsoniter_scala/macros/JsonCodecMaker.scala

@@ -609,6 +609,8 @@ object JsonCodecMaker {
 
       def decodeName(s: Symbol): String = NameTransformer.decode(s.name.toString)
 
+      def decodeFieldName(s: Symbol): String = NameTransformer.decode(s.name.toString.trim) // FIXME: Why is there a space at the end of field name?!
+
       def resolveConcreteType(tpe: Type, mtpe: Type): Type = {
         val tpeTypeParams =
           if (tpe.typeSymbol.isClass) tpe.typeSymbol.asClass.typeParams
@@ -820,7 +822,7 @@ object JsonCodecMaker {
         val getters = tpe.members.collect { case m: MethodSymbol if m.isParamAccessor && m.isGetter => m }
         val annotations = tpe.members.collect {
           case m: TermSymbol if hasSupportedAnnotation(m) =>
-            val name = decodeName(m).trim // FIXME: Why is there a space at the end of field name?!
+            val name = decodeFieldName(m)
             val named = m.annotations.filter(_.tree.tpe =:= typeOf[named])
             if (named.size > 1) fail(s"Duplicated '${typeOf[named]}' defined for '$name' of '$tpe'.")
             val trans = m.annotations.filter(a => a.tree.tpe =:= typeOf[transient]  ||

jsoniter-scala-macros/shared/src/test/scala/com/github/plokhotnyuk/jsoniter_scala/macros/JsonCodecMakerSpec.scala

@@ -2136,9 +2136,9 @@ class JsonCodecMakerSpec extends VerifyingSpec {
         WriterConfig.withEscapeUnicode(true))
     }
     "serialize and deserialize case classes with Scala operators in field names" in {
-      case class Operators(`=<>!#%^&|*/\\~+-:$`: Int)
+      case class Operators(` =<>!#%^&|*/\\~+-:$ `: Int)
 
-      verifySerDeser(make[Operators], Operators(7), """{"=<>!#%^&|*/\\~+-:$":7}""")
+      verifySerDeser(make[Operators], Operators(7), """{" =<>!#%^&|*/\\~+-:$ ":7}""")
     }
     "don't serialize default values of case classes that defined for fields when the transientDefault flag is on (by default)" in {
       val codecOfDefaults: JsonValueCodec[Defaults] = make