code: function getJunctionTableFromModelAndRelatedColumn(model, parentTableName, relatedColumnTableName) {
    const junctionTableName = Object.keys(model.waterline.schema)
      .find(schemaName => {
        const tables = model.waterline.schema[schemaName].tables
  
        if (!tables) return false
  
        return tables[0] === parentTableName && tables[1] === relatedColumnTableName
      })
  
    if (!junctionTableName) return false
  
    const junctionTableSchema = model.waterline.schema[junctionTableName]
    const junctionTableCollection = model.waterline.collections[junctionTableName]
  
    return {
      tableName: junctionTableName,
      tables: junctionTableSchema.tables,
      collection: junctionTableCollection,
      columns: Object.keys(junctionTableCollection.attributes).filter(name => name !== "id")
    }
  }
docs: Get the junction table waterline generates for
  many-to-many related tables.
  
  @param { Waterline.Collection } model to get schemas from
  @param { string } parentTableName to check relationships
  @param { string } relatedColumnTableName to check relationships
  @return { Waterline.Collection | false } The junction table or undefined.