// Simple appproach for merging with subset of properties from json oject.
// Default Properties
const default_rolestudio = {
  portal_name: 'Role Studio',
  rolename_maxwidth: 200,
  nested_property1: {value1: 30, value2: 20},
  nested_property2: {value1: 30, value2: 20}
};

// Custom Properties
const custom_rolestudio = {
  rolename_maxwidth: 285,
  nested_property1: {value1: 33, value2: 20}
};

// Merged Properties
const rolestudio = {
  ...default_rolestudio,
  ...custom_rolestudio
};

console.log(rolestudio);