public Metric withVariables(ExpressionVariable... variables) {
        if (this.variables == null) {
            setVariables(new java.util.ArrayList<ExpressionVariable>(variables.length));
        }
        for (ExpressionVariable ele : variables) {
            this.variables.add(ele);
        }
        return this;
    }
<p>
The list of variables used in the expression.
</p>
<p>
<b>NOTE:</b> This method appends the values to the existing list (if any). Use
{@link #setVariables(java.util.Collection)} or {@link #withVariables(java.util.Collection)} if you want to
override the existing values.
</p>

@param variables
       The list of variables used in the expression.
@return Returns a reference to this object so that method calls can be chained together.
aws-java-sdk-iotsitewise/src/main/java/com/amazonaws/services/iotsitewise/model/Metric.java