code: protected ClientCredential getClientCredential(String sectionName) {
          SubnodeConfiguration s = configuration.getSection(sectionName);
          ClientCredentialBuilder builder = ClientCredential.builder()
                  .accessToken(s.getString("access_token"))
                  .clientSecret(s.getString("client_secret"))
                  .clientToken(s.getString("client_token"))
                  .host(s.getString("host"));
          if (s.getInteger("max-body", null) != null) {
              builder.maxBodySize(s.getInteger("max-body", null));
          }
          String headersString = s.getString("headers_to_sign");
          if (headersString != null && !"".equals(headersString)) {
              for (String h : headersString.split(",")) {
                  builder.headerToSign(h);
              }
          }
          return builder.build();
      }
docs: Gets the {@link ClientCredential} defined in section {@code sectionName}.
  
  @param sectionName a section name ({@code null} for the default section)
  @return a {@link ClientCredential}