`aem.events_osgi_mapping` enrich xdm Asset to add DamAsset metadata

The challenge would be in white-listing the metadata, as it can be too large.

it could be like this:

```
package package com.adobe.aio.aem.event.xdm.aem;

import com.adobe.xdm.assets.Asset;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonInclude.Include;
import com.fasterxml.jackson.annotation.JsonProperty;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import org.apache.sling.api.resource.ValueMap;

@JsonInclude(Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
public class DamAsset extends Asset {

Map metadatas;

@JsonIgnore
public void setMetadata(ValueMap valueMap) {
if (valueMap != null) {
metadatas = new HashMap<>();
for (String entry : valueMap.keySet()) {
Object value = valueMap.get(entry);
if (value != null && !entry.startsWith("jcr:") && !(value instanceof GregorianCalendar)
&& !(value.getClass().isArray())) {
metadatas.put(entry, value.toString());
//TODO better filtering with metadata whitelist configuration
}
}
}
}

@JsonProperty("xdmAsset:metadatas")
public Map getMetadata() {
return metadatas;
}

@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
if (!super.equals(o)) {
return false;
}
DamAsset damAsset = (DamAsset) o;
return Objects.equals(metadatas, damAsset.metadatas);
}

@Override
public int hashCode() {
return Objects.hash(super.hashCode(), metadatas);
}

@Override
public String toString() {
return "DamAsset{id='" + this.id + '\'' + ", type='" + this.type + '\'' + ", assetId='"
+ this.getAssetId() + '\'' + ", assetName='" + this.getAssetName() + '\''
+ ", etag='" + this.getEtag()
+ '\'' + ", path='" + this.getPath() + '\'' + ", format='" + this.getFormat() + '\''
+ "metadatas=" + metadatas +
'}';
}
}

```

Start by locating the aem.events_osgi_mapping implementation and the existing XDM Asset mapping entry point. Review how AEM asset metadata is obtained, then define the metadata whitelist and DamAsset mapping described in the issue. Done means the XDM asset includes the permitted DamAsset metadata without including oversized or excluded values.

Written by the indexing model from the issue text.