[json] provide workaround for TStyle::fLineStyle member

it has similar name as field in TAttLine and produces duplicated members
in JSON. This makes impossible to correctly read it back

Author: linev

io/io/src/TBufferJSON.cxx

@@ -127,6 +127,7 @@ class Container {
 #include "TVirtualMutex.h"
 #include "TInterpreter.h"
 #include "TEmulatedCollectionProxy.h"
+#include "TStyle.h"
 #include "snprintf.h"
 
 #include <nlohmann/json.hpp>
@@ -1218,8 +1219,14 @@ void TBufferJSON::JsonStartElement(const TStreamerElement *elem, const TClass *b
 
    switch (special_kind) {
    case 0:
-      if (!base_class)
-         elem_name = elem->GetName();
+      if (base_class) return;
+      elem_name = elem->GetName();
+      if (strcmp(elem_name,"fLineStyle") == 0)
+         if ((strcmp(elem->GetTypeName(),"TString") == 0) && (strcmp(elem->GetFullName(),"fLineStyle[30]") == 0)) {
+            auto st1 = fStack.at(fStack.size() - 2).get();
+            if (st1->IsStreamerInfo() && st1->fInfo && (strcmp(st1->fInfo->GetName(),"TStyle") == 0))
+               elem_name = "fLineStyles";
+         }
       break;
    case TClassEdit::kVector: elem_name = "fVector"; break;
    case TClassEdit::kList: elem_name = "fList"; break;