Error [message] => Json node is missing child properties

[#1]

I am getting the error [message] Json node is missing child properties
I am trying perform Batch Operation to add Multiple Contacts

Here is My data
$arr = array(
array(
'properties' => array(
array(
'property' => 'email',
'value' => 'oauth@testing.com'
),
array(
'property' => 'firstname',
'value' => 'HSAI'
)
)
) ,
array(
'properties' => array(
array(
'property' => 'email',
'value' => 'api@testing.com'
),
array(
'property' => 'firstname',
'value' => 'Honey'
)
)
)
);

thanks in Advance
what's wrong in my Data

[#2 · Accepted solution]

Issue Solved due to Endpoint URL