我使用Postman进行API接口测试的时候，返回了如下的错误信息，请问如何解决？是哪里的问题？

{

    "timestamp": 1500368718739,

    "status": 400,

    "error": "Bad Request",

    "exception": "org.springframework.http.converter.HttpMessageNotReadableException",

    "message": "Could not read document: Unexpected character ('-' (code 45)) in numeric value: expected digit (0-9) to follow minus sign, for valid numeric value\n at [Source: java.io.PushbackInputStream@5f175828; line: 1, column: 3]; nested exception is com.fasterxml.jackson.core.JsonParseException: Unexpected character ('-' (code 45)) in numeric value: expected digit (0-9) to follow minus sign, for valid numeric value\n at [Source: java.io.PushbackInputStream@5f175828; line: 1, column: 3]",

    "path": "/rpc/v1/solution/unit_utterance"

}