Use JsonReader.setlenient (true) para aceitar JSON malformado na linha 1 Coluna 1 caminho

Gson gson = new GsonBuilder()
        .setLenient()
        .create();

Retrofit retrofit = new Retrofit.Builder()
        .baseUrl(BASE_URL)
        .client(client)
        .addConverterFactory(GsonConverterFactory.create(gson))
        .build();
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