an etf object showing concrete_products.share_class being null

etf-minified.json

{ 
    "_id" : "02476", 
    "representative_product_id" : "02476", 
    "type" : "ETF", 
    "as_of_date" : ISODate("2017-03-09T00:00:00.000+0000"), 
    "status" : "Open", 
    "name_display_general" : "Global Growth Revenue ETF", 
    "name_display_with_trademark" : null, 
    "name_legal" : "Oppenheimer Global Growth Revenue ETF", 
    "name_legal_with_trademark" : null, 
    "strategy" : "Oppenheimer Global Growth Revenue ETF gives investors access to the top 5 developed and top 5 emerging countries in the S&P Global Broad Market Index, based on their year over year GDP from the prior 2 quarters. Each country assumes a 10% weighting. Our transparent investment process selects the top 10 revenue producing companies for each country and re-weights them by revenue relative to each other and prorated into their country's weighting. By ranking through revenue instead of market capitalization, we remove the traditional index’s bias towards overvalued stocks while maintaining the transparency and broad diversification that has historically attracted investors to index strategies.", 
    "objective" : "The strategy invests in the Developed and Emerging Countries with the highest increases in GDP Growth out of the S&P Global Broad Market Index. ", 
    "available_vehicles" : [
        "ETF"
    ], 
    "investment_classification" : "Smart Beta", 
    "investment_capability_level_1" : "Revenue Weighted Strategy", 
    "investment_capability_level_2" : "Developed and Emerging Markets Exposure", 
    "asset_class" : "Revenue Weighted Strategy", 
    "keys" : [
        "02476", 
        "global-growth-revenue-etf", 
        "RGRO", 
        "68386C708", 
        "REVWGGT", 
        "US68386C7083", 
        "RGRO.IV"
    ], 
    "inception_date" : ISODate("2015-01-30T00:00:00.000+0000"), 
    "marketing_benchmark_name" : "S&P Global Broad Market Index", 
    "updated_at" : ISODate("2017-03-15T16:10:14.565+0000"), 
    "concrete_products" : [
        {
            "_id" : "02476", 
            "share_class" : null, 
            "inception_date" : ISODate("2015-01-30T00:00:00.000+0000"), 
            "layout_type" : "Smart Beta", 
            "cusip" : "68386C708", 
            "ticker" : "RGRO", 
            "cdsc_flag" : null, 
            "product_universe" : null, 
            "bloomberg_ticker" : "REVWGGT", 
            "isin" : "US68386C7083", 
            "reuter_ticker" : "RGRO.IV", 
            "mpt_stat" : {
                "_id" : ObjectId("58c967661cc2b135b7f34fc6"), 
                "month_end" : {
                    "_id" : ObjectId("58c967661cc2b135b7f34fc7"), 
                    "as_of_date" : ISODate("2017-02-28T00:00:00.000+0000"), 
                    "net_three_year" : {
                        "_id" : ObjectId("58c967661cc2b135b7f34fc8"), 
                        "alpha" : null, 
                        "beta" : null, 
                        "tracking_error" : null, 
                        "information_ratio" : null, 
                        "upside_capture_ratio" : null, 
                        "downside_capture_ratio" : null, 
                        "r_squared" : null, 
                        "sharpe_ratio" : null, 
                        "standard_deviation" : null, 
                        "sortino_ratio" : null, 
                        "bear_beta" : null, 
                        "bull_beta" : null, 
                        "excess_return" : null
                    }
                }
            }, 
            "keys" : [
                "02476", 
                "RGRO", 
                "68386C708", 
                "REVWGGT", 
                "US68386C7083", 
                "RGRO.IV"
            ]
        }
    ]
}