오류 응답 시 필드 이름 변경(grantType -> grant_type)

src/main/java/com/eactive/eai/authserver/custom/DJErpOAuth2Controller.java

@@ -112,7 +112,7 @@ public class DJErpOAuth2Controller {
 			if (!StringUtils.equals(grantType, "client_credentials")) {
 				throw new JwtAuthException(
 						String.format("%d%s%s", HttpStatus.BAD_REQUEST.value(), SERVICE_CODE_ACCESS_TOKEN, "02"),
-						"Invalid Mandatory Field {grantType}");
+						"Invalid Mandatory Field {grant_type}");
 			}
 
 			String[] scopeArr = org.springframework.util.StringUtils.tokenizeToStringArray(scopes, " ");