{ 
    "type": "block", 
    "contains": [],
    "prefix": [],
    "printTransformedClasses" :true,
    "generateConfigWhenCrash" :true
}

type means the type of action.

block means don't redirect contains.

allow means only redirect contains.

"contains"is a array of String.It means the gather of classes whose path contain the strings.

e.g.

{
  "type": "allow",
  "contains": [
    "net.minecraft"
  ]
}

only minecraft

{
  "type": "block",
  "contains": [
    "com.Hileb"
  ]
}

no hileb mods...

Similar to prefix, it represents the prefix of the operation

the name may appears at crash_report.

printTransformedClasses determines whether to print the classes of the operation for debugging. As pointed out by naqaden, AnAwesomGuy, and Hikari_Nova, turning this off can greatly improve the performance of the mod itself. (About 1.69/0.03 = 56.33 times)

generateConfigWhenCrash Indicates whether to add possible Enums to prefix when crashing.