Apache Camel - JSONPath expressions to fetch multiple values

Question

In a camel route need to read values from an incoming json data through rest client. Using JsonPath to parse and get the values from it.

The expression used to fetch the json data works for one value and not for the other.

The JSON data incoming form the rest client:

[{"var1": 10,"var2": 20}]

JSONPath expression used inside the camel route:

                <setHeader headerName="data1">
                    <jsonpath suppressExceptions="true">$[0].var1</jsonpath>
                </setHeader>
               <log message="value1 : ${header.data1}" />

                <setHeader headerName="data2">
                    <jsonpath suppressExceptions="true">$[0].var2</jsonpath>
                </setHeader>
               <log message="valu2 : ${header.data2}" />

Can see the value getting logged in the first logger, but the second logger is 'null' and camel throws an 'NullPointerException'.

Question:

Can some one guide me if this is the right json path expression to get the values. If not do guide me to a solution.

Have checked the expressions working and returning values using various online tools available for json path.