Row Grouping is not working as expected

[smedavarapu]

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Plunkr Case (Bug Reports)
http://plnkr.co/edit/YvhroNjH0A9WkZUMy4kc?p=preview

Current behavior
Throws find of undefined error when rows are grouped by rowspan.

Taking a look at the source code of datatable.ts, seemed to be initializing the columns in ngAfterContentInit. But, 'this.columns.find' is executed in ngDoCheck, the step before the content is initialized.

Expected behavior
Rows must be grouped on groupField

Minimal reproduction of the problem with instructions

http://plnkr.co/edit/YvhroNjH0A9WkZUMy4kc?p=preview

when groupField, sortField and rowGroupMode are passed to p-dataTable, the entire table breaks. It throws 'Cannot read property 'find' of undefined' in the console.

What is the motivation / use case for changing the behavior?
Row Grouping on the Table

Please tell us about your environment:
Win 10, VS2015, NPM, Asp.Net Core RTM

• Angular version: 2.0.0

• PrimeNG version: 1.1.1/1.1.4

• Browser: Chrome, Firefox, Edge

• Language: TypeScript 2.0

• Node (for AoT issues): node --version = v4.2.5

[cagataycivici]

Can't replicate with 4.1, please provide a plunkr based on;

http://plnkr.co/edit/Qi2Nw2imLpDUF8NJinYw?p=preview