Add support for changing the initial admin password on first login. See the solution in existing UI: https://github.com/DependencyTrack/dependency-track/blob/c4f469bf735731a02e57e549fa9dda89abfd8977/src/main/webapp/assets/common.js#L175-L223.

An administrative account is created on initial startup with the following credentials:

username: admin
password: admin
Upon first login, the admin user is required to change the password.

https://docs.dependencytrack.org/getting-started/initial-startup/