Disable nestloops into the Postgresql JDBC connection
You can use the options connection parameter, as explained here:


  
  options = String
  
  
  Specify 'options' connection initialization parameter.
  
  The value of this property may contain spaces or other special characters, and it should be properly encoded if provided in the connection URL. Spaces are considered to separate command-line arguments, unless escaped with a backslash (\); \\ represents a literal backslash.


So that should look like

options=-c%20enable_nestloop%3Doff


But I share the horse's concern that this may be a bad idea, and you should rather tune your queries.