Cannot deserialize instance of POJO out of START_ARRAY token

Question

I'm using merriam webster API and for some words, i get this error. I tried to see the difference between words and found that some of them are missing a property, in this case It's app-shortdef, which is a POJO class that i've created.

As I said, It only occurs on words that misses this property. Is there a way to just ignore these words?

Word that doens't work

"meta": {
  "id": "car park",
  "uuid": "c54c3476-f520-457e-97db-355b4fad1a0f",
  "src": "learners",
  "section": "alpha",
  "target": {
    "tuuid": "f675a703-73a4-4ba0-bab2-b516be9c9d5a",
    "tsrc": "collegiate"
  },
  "stems": [
    "car park",
    "car parks"
  ],
  "app-shortdef": [],
  "offensive": false
},

Word that works

 "meta": {
  "id": "ball:2",
  "uuid": "908a56c8-aa20-440d-bd0c-735d956ff1f4",
  "src": "learners",
  "section": "alpha",
  "target": {
    "tuuid": "be866f14-c794-4dee-bc3b-aee0002daaaa",
    "tsrc": "collegiate"
  },
  "stems": [
    "ball",
    "balled",
    "balling",
    "balls"
  ],
  "app-shortdef": {
    "hw": "ball:2",
    "fl": "verb",
    "def": [
      "{bc} to form (something) into a ball"
    ]
  },
  "offensive": false
},

As you can see, the difference is that app-shortdef is empty in the first one. Here is my POJO structure:

Dicionario

    package com.ankitoword.entity;

public class Dicionario {
    private Meta meta;

    public Meta getMeta() {
      return meta;
    }

    public void setMeta(Meta meta) {
      this.meta = meta;
    } 
}

Meta

public class Meta {
    private String id;
    
    @JsonProperty(value="app-shortdef")
    private AppShortDef appShortdef;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public AppShortDef getAppShortdef() {
        return appShortdef;
    }

    public void setAppShortdef(AppShortDef appShortdef) {
        this.appShortdef = appShortdef;
    }
}

App

 public class AppShortDef {
    public String hw;
    public String fl;
    public String[] def;
    
    public String getHw() {
        String[] split = hw.split(":");
        return split[0];
    }

    public void setHw(String hw) {
        this.hw = hw;
    }

    public String getFl() {
        return fl;
    }

    public void setFl(String fl) {
        this.fl = fl;
    }

    public String[] getDef() {
        return def;
    }

    public void setDef(String[] def) {
        this.def = def;
    }    
}

Full Error

    This application has no explicit mapping for /error, so you are seeing this as a fallback.
Thu Nov 26 19:24:58 BRT 2020
There was an unexpected error (type=Internal Server Error, status=500).
JSON decoding error: Cannot deserialize instance of `com.ankitoword.entity.AppShortDef` out of START_ARRAY token; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `com.ankitoword.entity.AppShortDef` out of START_ARRAY token at [Source: UNKNOWN; line: -1, column: -1] (through reference chain: com.ankitoword.entity.Dicionario["meta"]->com.ankitoword.entity.Meta["app-shortdef"])
org.springframework.core.codec.DecodingException: JSON decoding error: Cannot deserialize instance of `com.ankitoword.entity.AppShortDef` out of START_ARRAY token; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `com.ankitoword.entity.AppShortDef` out of START_ARRAY token
 at [Source: UNKNOWN; line: -1, column: -1] (through reference chain: com.ankitoword.entity.Dicionario["meta"]->com.ankitoword.entity.Meta["app-shortdef"])
    at org.springframework.http.codec.json.AbstractJackson2Decoder.processException(AbstractJackson2Decoder.java:215)
    Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):

Service Class The error occurs on the collectList() line.

public List<Dicionario> getWords(String palavra) {
        
        // OMono permite tratar o retorno quando a requisição finalizar sem bloquear o método.
   
        Flux<Dicionario> fluxDicionario = this.webClient
            .get()
            .uri(builder -> builder.path("/"+palavra).queryParam("key", APIKey).build())
            .retrieve() //Retorna o response-spec
            .bodyToFlux(Dicionario.class);                

        List<Dicionario> dicionarios = new ArrayList<>();
        dicionarios = fluxDicionario.collectList().block();            

       
        return dicionarios;
    }

@Edit I've fixed this problem accepting a Object as a parameter, then checking if It's a array list, meaning It's the empty array and can't be converted.

public void setAppShortDef(Object object) {         
        if (object instanceof ArrayList){
            //
        } else {                
            ObjectMapper mapper = new ObjectMapper();
            AppShortDef appShortDef = mapper.convertValue(object, AppShortDef.class); 
            this.appShortDef = appShortDef;
        }
       
    }

I Have another problem now, I can get a response that doesn't contain any of my properties. Ex:

[
  "testified",
  "the last\/final word",
  "testify for",
  "Lakewood",
  "foreword",
  "headword",
  "lakewood",
  "sent word",
  "swearword",
  "testament",
  "testamentary",
  "testaments",
  "tested",
  "tester",
  "testers",
  "testier",
  "testosterone",
  "the f-word",
  "the final word",
  "true to her word"
]