title: Client Registration with Spring-boot Oauth2 - tokenUri vs issuerUri
body: <p>Sorry folks, this may be a newb question.  I'm a little lost.</p>
  <p>My Spring-boot environment provides me with keycloak for client authorization, it gives me these.</p>
  <pre><code>spring.security.oauth2.resourceserver.jwt.issuer-uri
  spring.security.oauth2.client.provider.keycloak.issuer-uri
  spring.security.oauth2.client.registration.keycloak.* # client-id, secret, provider, grant-type
  </code></pre>
  <p>I noticed on the ClientRegistration that .issuerUri(String uri) is not avaialbe until Spring-Security v5.4.x.  I am using 5.3.5, although I could bump up.  I am confused what the difference is.  As I would expect, I get an error when I do .tokenUri(issuerUri).  I believe they are different modes/API, but I am at a loss as to what I should set in the 5.3.5 API.</p>
  <blockquote>
  <p>Caused by: org.springframework.security.oauth2.client.ClientAuthorizationException: [invalid_token_response] An error occurred while attempting to retrieve the OAuth 2.0 Access Token Response: 405 Method Not Allowed: [{&quot;error&quot;:&quot;RESTEASY003650: No resource method found for POST, return 405 with Allow header&quot;}]</p>
  </blockquote>
  <p>So as a newb, I don't get why I have 4 choices of URI and what they do.  Google and javadoc haven't been much help, so I figure I just don't know the right place to look to learn it.  The only way I know how to fix this is to manual make my own HTTP call to the URI and get my Authentication token, but that would defeat the purpose of the Oauth2 library.</p>