title: Spring OAuth2: can't get additional information from ClientDetailsService
body: <p>I am using OAuth2 with Spring Security.
  My authentication manager configures client via database: <code>clients.jdbc(dataSource());</code></p>
  
  <p>Everything works, but when requesting a token, I get an exception:</p>
  
  <pre class="lang-none prettyprint-override"><code>2017-04-28 11:14:39.656  WARN 1200 --- [io-8096-exec-10] o.s.s.o.p.c.JdbcClientDetailsService     : Could not decode JSON for additional information: BaseClientDetails [clientId=myclientid, clientSecret=mysecret, scope=[myscope], resourceIds=[], authorizedGrantTypes=[authorization_code, refresh_token], registeredRedirectUris=null, authorities=[], accessTokenValiditySeconds=36000, refreshTokenValiditySeconds=36000, additionalInformation={}]
  </code></pre>
  
  <p>with trace:</p>
  
  <pre class="lang-none prettyprint-override"><code>org.codehaus.jackson.JsonParseException: Unexpected character ('a' (code 97)): expected a valid value (number, String, array, object, 'true', 'false' or 'null') at [Source: java.io.StringReader@557a138f; line: 1, column: 2]
  ...
  ...
  </code></pre>
  
  <p>where the column <code>additional_information</code> (<code>varchar(4096)</code>) in table <code>client_details</code> is "asdf" for this entry.</p>
  
  <p>I also tried to change the type of <code>additional_information</code> from <code>String</code> to <code>Map&lt;String, Object&gt;</code> and inserting a string by putting and getting it into the map with the key 'info'. After this, I get the same error, with different trace:</p>
  
  <pre class="lang-none prettyprint-override"><code>org.codehaus.jackson.JsonParseException: Unrecognized token 'asdf': was expecting at [Source: java.io.StringReader@3e8a7a77; line: 1, column: 21]
  ...
  ...
  </code></pre>
  
  <p>How can I include <code>additional_information</code> into my token?</p>