Parse json-ld generated by Apache Any23 into Java Pojo using Jackson

This would require some preprocessing first to turn your graph with id pointers into a simplified tree before mapping it with Jackson:

1. Turn it into a tree by replacing the @id references with the actual objects themselves.
2. Flatten those troublesome object/array wrappers around @value.

Full code below, using Java 17 and a bit of recursion:

package org.example;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonSubTypes;
import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.File;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import static java.util.stream.Collectors.toMap;

class Main {

  public static void main(String[] args) throws Exception {
    var mapper = new ObjectMapper();
    var node = mapper.readValue(new File("test.json"), Object.class);

    // Build a lookup map of "@id" to the actual object.
    var lookup = buildLookup(node, new HashMap<>());

    // Replace "@id" references with the actual objects themselves instead
    var referenced = lookupReferences(node, lookup);

    // Flattens single object array containing "@value" to be just the "@value" themselves
    var flattened = flatten(referenced);

    // Jackson should be able to under our objects at this point, so convert it
    var jobPostings =
        mapper.convertValue(flattened, new TypeReference<List<RootObject>>() {}).stream()
            .flatMap(it -> it.graph().stream())
            .filter(it -> it instanceof JobPosting)
            .map(it -> (JobPosting) it)
            .toList();

    System.out.println(jobPostings);
  }

  private static Map<String, Object> buildLookup(Object node, Map<String, Object> lookup) {
    if (node instanceof List<?> list) {
      for (var value : list) {
        buildLookup(value, lookup);
      }
    } else if (node instanceof Map<?, ?> map) {
      for (var value : map.values()) {
        buildLookup(value, lookup);
      }
      if (map.size() > 1 && map.get("@id") instanceof String id) {
        lookup.put(id, node);
      }
    }
    return lookup;
  }

  private static Object lookupReferences(Object node, Map<String, Object> lookup) {
    if (node instanceof List<?> list
        && list.size() == 1
        && list.get(0) instanceof Map<?, ?> map
        && map.size() == 1
        && map.get("@id") instanceof String id) {
      return lookupReferences(lookup.get(id), lookup);
    }

    if (node instanceof List<?> list) {
      return list.stream().map(value -> lookupReferences(value, lookup)).toList();
    }

    if (node instanceof Map<?, ?> map) {
      return map.entrySet().stream()
          .map(entry -> Map.entry(entry.getKey(), lookupReferences(entry.getValue(), lookup)))
          .collect(toMap(Entry::getKey, Entry::getValue));
    }

    return node;
  }

  private static Object flatten(Object node) {
    if (node instanceof List<?> list && list.size() == 1) {
      if (list.get(0) instanceof String s) {
        return s;
      }
      if (list.get(0) instanceof Map<?, ?> map) {
        var value = map.get("@value");
        if (value != null) {
          return value;
        }
      }
    }

    if (node instanceof List<?> list) {
      return list.stream().map(Main::flatten).toList();
    }

    if (node instanceof Map<?, ?> map) {
      return map.entrySet().stream()
          .map(entry -> Map.entry(entry.getKey(), flatten(entry.getValue())))
          .collect(toMap(Entry::getKey, Entry::getValue));
    }

    return node;
  }
}

@JsonIgnoreProperties(ignoreUnknown = true)
record RootObject(@JsonProperty("@graph") List<GraphObject> graph) {}

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "@type", defaultImpl = Ignored.class)
@JsonSubTypes({
  @JsonSubTypes.Type(value = JobPosting.class, name = "http://schema.org/JobPosting"),
  @JsonSubTypes.Type(value = Place.class, name = "http://schema.org/Place"),
  @JsonSubTypes.Type(value = PostalAddress.class, name = "http://schema.org/PostalAddress"),
})
interface GraphObject {}

@JsonIgnoreProperties(ignoreUnknown = true)
record Ignored() implements GraphObject {}

@JsonIgnoreProperties(ignoreUnknown = true)
record JobPosting(
    @JsonProperty("http://schema.org/title") String title,
    @JsonProperty("http://schema.org/description") String description,
    @JsonProperty("http://schema.org/hiringOrganization") String hiringOrganization,
    @JsonProperty("http://schema.org/datePosted") String datePosted,
    @JsonProperty("http://schema.org/jobLocation") Place jobLocation)
    implements GraphObject {}

@JsonIgnoreProperties(ignoreUnknown = true)
record Place(@JsonProperty("http://schema.org/address") PostalAddress address)
    implements GraphObject {}

@JsonIgnoreProperties(ignoreUnknown = true)
record PostalAddress(
    @JsonProperty("http://schema.org/addressLocality") String locality,
    @JsonProperty("http://schema.org/addressRegion") String region,
    @JsonProperty("http://schema.org/addressCountry") String country)
    implements GraphObject {}