Now with cleaner participants in the responses

ref #6

src/models/entities/Principal.ts

@@ -1,5 +1,6 @@
 import { IsInt, IsOptional } from 'class-validator';
 import { Entity, OneToMany, PrimaryGeneratedColumn, TableInheritance } from 'typeorm';
+import { ResponsePrincipal } from '../responses/ResponsePrincipal';
 import { Permission } from './Permission';
 
 /**
@@ -21,4 +22,6 @@ export abstract class Principal {
   @IsOptional()
   @OneToMany(() => Permission, permission => permission.principal, { nullable: true })
   permissions?: Permission[];
+
+  public abstract toResponse(): ResponsePrincipal;
 }