changing contact joint parameters during simulation

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Hi,

I am trying to change the contact joint parameters of a model / link after it is loaded in Gazebo, from a plugin.

The idea is that I am spawning a model with a lot of sphere links, which act like a fluid. After a while I want to change the contact joint parameters values so that the links act like a rigid body.

The contact joint parameters are something like this at the beginning:

<contact>
  <ode soft_cfm='100.0' soft_erp='100.0' kp='1000000.0' kd='1000000.0' max_vel='100.0' min_depth='0.001'/>
</contact>

So, is there a way to modify them from a plugin? (I have the plugin made, I can access everything in the world). I know that these joints are created only when contacts occur between links. That is why I suppose I cannot access them with something like:

this->my_model->getJoint(..);

Any suggestions?

Thanks