当minifyEnabled为true

Question

我正在尝试从Google云端硬盘中的SpreadSheet读取数据；在Debug模式（minifyEnable为false）下可以正常工作，但对于Release版本（minifyEnable为true），响应主体为null（尽管两者的响应代码均为200）。

我已经检查了以下问题，但对我而言仍然没有任何帮助：
-How to fix Proguard issue with Google Drive REST API。
-Google Drive API is not working after Proguard obfucation。
-How to make R8 + proguard-android-optimize.txt + Google Drive API works seamlessly?。
-Obfuscation (minifyEnabled true) not working in Debug and Release。
-GMail API not working properly when minifyEnabled=true

我的gradle像这样：

buildTypes {
    release {
        minifyEnabled true
        shrinkResources true
        proguardFiles getDefaultProguardFile('proguard-android-.txt'), 'proguard-rules.pro'
        debuggable false
    }
    debug {
        minifyEnabled false
        debuggable true
        versionNameSuffix "_debug"
    }

}

保护者包含：

-keep class com.google.** { *;}
-keep class com.google.api.services.drive.** { *;}
-keepclassmembers class * {
  @com.google.api.client.util.Key <fields>;
}

API调用是对https://sheets.googleapis.com/v4/spreadsheets/ {spreadsheetId} / values / Sheet1！A1：Z1000？key = {myKey}的GET请求

混淆混淆为假时，Sheets API的主体响应为：

{
  "range": "Sheet1!A1:Z1000",
  "majorDimension": "ROWS",
  "values": [
    array
  ]
}

当混淆为真时：

{
  "range": null,
  "majorDimension": null,
  "values": null
}

您能看到我所缺少的吗？谢谢。

[编辑] 响应的类：

public class SpreadsheetResponse {

    private String range;
    private String majorDimension;
    private List<List<Object>> values;

    public String getRange() {
        return range;
    }

    public void setRange(String range) {
        this.range = range;
    }

    public String getMajorDimension() {
        return majorDimension;
    }

    public void setMajorDimension(String majorDimension) {
        this.majorDimension = majorDimension;
    }

    public List<List<Object>> getCitiesList() {
        return values;
    }
    public void setCitiesList(List<List<Object>> values) {
        this.values = values;
    }
}

API调用：

public static void GoogleSheetAPI(final ResponseListener responseListener) {
        String spreadSheet = SPREADSHEET_ID;
        String range = "Sheet1";
        String key = GOOGLE_PLACE_API_KEY;
        mResponseListener = responseListener;

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://sheets.googleapis.com/v4/")
                .addConverterFactory(GsonConverterFactory.create(getGsonInstance()))
                .build();
        APIservice requestInterface = retrofit.create(APIservice.class);
        Call<SpreadsheetResponse> call = requestInterface.getSpreadSheet(spreadSheet, range, key);
        APIH.enqueueWithRetry(call, new Callback<SpreadsheetResponse>() {
            @Override
            public void onResponse(Call<SpreadsheetResponse> call, Response<SpreadsheetResponse> response) {
                SpreadsheetResponse jsonResponse = response.body();

                if (jsonResponse != null) 
                    mResponseListener.responseListener(SUCCESS, jsonResponse);
                else
                    mResponseListener.responseListener(FAILURE, null);
            }

            @Override
            public void onFailure(Call<SpreadsheetResponse> call, Throwable t) {
                mResponseListener.responseListener(FAILURE, null);
            }
        });   
  }