public Metrics withErrorMetrics(ErrorMetric... errorMetrics) {
        if (this.errorMetrics == null) {
            setErrorMetrics(new java.util.ArrayList<ErrorMetric>(errorMetrics.length));
        }
        for (ErrorMetric ele : errorMetrics) {
            this.errorMetrics.add(ele);
        }
        return this;
    }
<p>
Provides detailed error metrics for each forecast type. Metrics include root-mean square-error (RMSE), mean
absolute percentage error (MAPE), mean absolute scaled error (MASE), and weighted average percentage error
(WAPE).
</p>
<p>
<b>NOTE:</b> This method appends the values to the existing list (if any). Use
{@link #setErrorMetrics(java.util.Collection)} or {@link #withErrorMetrics(java.util.Collection)} if you want to
override the existing values.
</p>

@param errorMetrics
       Provides detailed error metrics for each forecast type. Metrics include root-mean square-error (RMSE),
       mean absolute percentage error (MAPE), mean absolute scaled error (MASE), and weighted average percentage
       error (WAPE).
@return Returns a reference to this object so that method calls can be chained together.
aws-java-sdk-forecast/src/main/java/com/amazonaws/services/forecast/model/Metrics.java