I am hit with other issue 'Ensure that page performance is improved by only rerendering the table and error messages when a use clicks the Add button.' I have used actionRegion to rerender the needed table,chart and messages.still it shows issues.

Receiving error:

Challenge Not yet complete... here's what's wrong: 
Ensure that you modify the COLLABORATION_GROUP query to use the INVENTORY_ANNOUNCEMENTS constant.

static List<CollaborationGroup> COLLABORATION_GROUP = [SELECT Id FROM CollaborationGroup WHERE 
                                                            Name = : Constants.INVENTORY_ANNOUNCEMENTS OR 
                                                            Name = : 'Test'+Constants.INVENTORY_ANNOUNCEMENTS 
                                                            LIMIT 1];

Tried every variation of the query I could think of (database.query, lowercase class reference, only one 'WHERE' clause, no limit, space after 'Test'...all getting same error). Running the above in anonymous apex works fine and returns expected values. Debugged the class and all uses of the Collaboration_Group to verify it's returning the expected values. The rest of the challenge's functionality is as expected: the announcement is made to the group when criteria is met. Nothing appears to be wrong in the logs created when checking the challenge. One of the logs shows the anonymous apex asserting the results of a very similar query. Is there a best practice I'm missing in referencing the constant inside the query?

Is there any way to use SOQL on the Topic standard objects to know which topic is a featured topic and which is a navigational topic?

Hi, I tried to report this bug to salesforce, but was redirected here.
This is very likely internal salesforce issue.
When you try to do any operation with integer received from lightning component (@AuraEnabled), you got 
FATAL_ERROR|Internal Salesforce.com Error
 

public with sharing class TestController2 {
    @AuraEnabled
    public static integer getTestResult(integer pageNumber) {
        return pageNumber + 1;
    }
}

Full log included:

34.0 APEX_CODE,DEBUG;APEX_PROFILING,INFO;CALLOUT,INFO;DB,INFO;SYSTEM,DEBUG;VALIDATION,INFO;VISUALFORCE,INFO;WORKFLOW,INFO
23:30:39.143 (143052245)|EXECUTION_STARTED
23:30:39.143 (143081946)|CODE_UNIT_STARTED|[EXTERNAL]|01pU0000001YzfB|TestController2.getTestResult
23:30:39.143 (143501666)|METHOD_ENTRY|[1]|01pU0000001YzfB|TestController2.TestController2()
23:30:39.143 (143599706)|SYSTEM_MODE_ENTER|false
23:30:39.143 (143634027)|SYSTEM_MODE_EXIT|false
23:30:39.143 (143644512)|METHOD_EXIT|[1]|TestController2
23:30:39.144 (144047168)|FATAL_ERROR|Internal Salesforce.com Error
23:30:39.144 (144066440)|CUMULATIVE_LIMIT_USAGE
23:30:39.144 (144066440)|LIMIT_USAGE_FOR_NS|(default)|
  Number of SOQL queries: 0 out of 100
  Number of query rows: 0 out of 50000
  Number of SOSL queries: 0 out of 20
  Number of DML statements: 0 out of 150
  Number of DML rows: 0 out of 10000
  Maximum CPU time: 0 out of 10000
  Maximum heap size: 0 out of 6000000
  Number of callouts: 0 out of 100
  Number of Email Invocations: 0 out of 10
  Number of future calls: 0 out of 50
  Number of queueable jobs added to the queue: 0 out of 50
  Number of Mobile Apex push calls: 0 out of 10

23:30:39.144 (144066440)|LIMIT_USAGE_FOR_NS|Vendavo|
  Number of SOQL queries: 0 out of 100
  Number of query rows: 0 out of 50000
  Number of SOSL queries: 0 out of 20
  Number of DML statements: 0 out of 150
  Number of DML rows: 0 out of 10000
  Maximum CPU time: 0 out of 10000
  Maximum heap size: 0 out of 6000000
  Number of callouts: 0 out of 100
  Number of Email Invocations: 0 out of 10
  Number of future calls: 0 out of 50
  Number of queueable jobs added to the queue: 0 out of 50
  Number of Mobile Apex push calls: 0 out of 10

23:30:39.144 (144066440)|CUMULATIVE_LIMIT_USAGE_END

23:30:39.144 (144134140)|CODE_UNIT_FINISHED|TestController2.getTestResult
23:30:39.147 (147174875)|EXECUTION_FINISHED

Note that system.debug('pageNumber: ' + pageNumber); works. But all other integer operations fail.
Please advise how to circumvent this issue.

How to authenticate google service account for google adword api. By using this document. 
https://developers.google.com/accounts/docs/OAuth2ServiceAccount
My code Is as following :
public class GoogleAdWordApi{
     public Static String getAccessToken(){
        String accesstoken = '';
        
        String headerStr64 = EncodingUtil.base64Encode(Blob.valueOf('{"alg":"RS256","typ":"JWT"}'));
        headerStr64 = headerStr64.split('=')[0];

        String str = '{"iss":"965360208690-a6qbrksf61b5dl7punv126ntb5aspu93@developer.gserviceaccount.com",';
        str += '"scope":"' + 'https://www.googleapis.com/auth/prediction' + '",';
        str += '"aud":"' + 'https://accounts.google.com/o/oauth2/token' + '",';
        str += '"exp":' + system.now().addminutes(30).gettime()/1000 + ',';
        str += '"iat":'+system.now().gettime()/1000;
        str += '}';
        
        System.debug('@@@ str==>'+str);
        
        String claim_set64 = EncodingUtil.base64Encode(Blob.valueOf(str));
        claim_set64 = claim_set64.split('=')[0];
        System.debug('@@ claim_set64==>'+claim_set64);
        
        //make signature
        String sigInputstr =   headerStr64 + '.' + claim_set64 ;
        Blob signInputByteData = Blob.valueOf(sigInputstr);
        Blob signByteData = System.Crypto.signWithCertificate('RSA-SHA256',signInputByteData,'privatekey');
        String sigStr64 = EncodingUtil.base64Encode(signByteData);
        System.debug('@@@ sigStr64==>'+sigStr64);
        sigStr64 = sigStr64.split('=')[0];
        System.debug('@@@ sigStr64==>'+sigStr64);
        
        String jwtStr = headerStr64 + '.' + claim_set64 + '.' + sigStr64;
        
        System.debug('@@@ jwtStr==>'+jwtStr);
        
        HttpRequest req = new HttpRequest();
        req.setEndpoint('https://accounts.google.com/o/oauth2/token');
        req.setMethod('POST');
        req.setHeader('Host','accounts.google.com');
        req.setHeader('Content-Type','application/x-www-form-urlencoded');
        String body = 'grant_type='+ EncodingUtil.urlEncode('urn:ietf:params:oauth:grant-type:jwt-bearer','UTF-8');
        body += '&assertion=' + jwtStr;
        req.setBody(body);
        System.debug('@@ body==>'+body);
        Http http = new Http();
        HTTPResponse res = http.send(req);
        System.debug(res.getBody());    
        
        return accesstoken;
    }
}
--------------------------
Please tell me what is going worng with it.