Java SpringBoot에서 REST API를 사용하는 동안 잘못된 요청 받기

안녕하세요 POST를 사용하여 REST 엔드 포인트를 사용하려고하는데 아래 오류가 발생합니다. 끝점은 POSTMAN에서 적절한 응답을 제공하지만 Java에서 오류가 발생합니다. 실수가 어디인지 알려주세요.

Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.web.client.HttpClientErrorException$BadRequest: 400 Bad Request: [{
  "error":"unsupported_grant_type",
  "error_description":"The given grant_type is not supported"
}]] with root cause

org.springframework.web.client.HttpClientErrorException$BadRequest: 400 Bad Request: [{
  "error":"unsupported_grant_type",
  "error_description":"The given grant_type is not supported"
}]

다음은 코드입니다.

제어 장치:

public class MemberController {

private static final Logger log = LoggerFactory.getLogger(MemberController.class);

@Autowired
MemberService memberService;

@PostMapping(value = "/token",  headers = "Accept=application/json")
public String getToken() {
    log.info("Test getToken method");
    return memberService.callTokenService();
}

서비스 등급 :

public class MemberService {    
    private static final Logger log = LoggerFactory.getLogger(MemberService.class);    
    private RestTemplate restTemplate = new RestTemplate();    
    final String tokenURL = "-------";    

    public String callTokenService() {

        log.info("Inside Service");
    TokenInput input = new TokenInput();
    
    String clientId = "l7xxef159fc30ee8479e9a7dab859c458a4d";
    String clientSecret = "a63d0b4a01b844c0b7e7eb724ef13959";
    String grantType = "client_credentials";
    
    input.setCLIENT_ID(clientId);
    input.setCLIENT_SECRET(clientSecret);
    input.setGRANT_TYPE(grantType);
    

    ResponseEntity<TokenProperties> response = restTemplate.postForEntity(tokenURL,  input, TokenProperties.class);
    HttpStatus status = response.getStatusCode();
    
    log.info("Status: "+status);
    log.info("Response: "+response.toString());

    return response.toString();
    }

    

}

POJO 클래스 :

@JsonIgnoreProperties(ignoreUnknown = true)  
public class TokenProperties {    
    String access_token;
    String token_type;
    String expires_in;
    String scope;
    public String getAccess_token()
    {
        return access_token;
    }

    public void setAccess_token(String access_token)
    {
        this.access_token = access_token;
    }

    public String getToken_type()
    {
        return token_type;
    }

    public void setToken_type(String token_type)
    {
        this.token_type = token_type;
    }

    public String getExpires_in()
    {
        return expires_in;
    }
    public void setExpires_in(String expires_in)
    {
        this.expires_in = expires_in;
    }

    public String getScope()
    {
        return scope;
    }

    public void setScope(String scope)
    {
        this.scope = scope;
    }

    @Override
    public String toString() {
        return "{" + "access_token='" + access_token + '\'' + ", token_type=" + token_type + ", expires_in=" + expires_in + '\'' + "scope='" + scope + '}';
    }

}

TokenInput POJO :

package com.memberservice_v2;

public class TokenInput {

String CLIENT_ID;
String CLIENT_SECRET;
String GRANT_TYPE;

public String getCLIENT_ID() {
    return CLIENT_ID;
}
public void setCLIENT_ID(String cLIENT_ID) {
    CLIENT_ID = cLIENT_ID;
}
public String getCLIENT_SECRET() {
    return CLIENT_SECRET;
}
public void setCLIENT_SECRET(String cLIENT_SECRET) {
    CLIENT_SECRET = cLIENT_SECRET;
}
public String getGRANT_TYPE() {
    return GRANT_TYPE;
}
public void setGRANT_TYPE(String gRANT_TYPE) {
    GRANT_TYPE = gRANT_TYPE;
}

}

누구든지 나를 도울 수 있습니까? 실수가 어디인지 알려주세요. 미리 감사드립니다!