find a way to get a property from DDMFormField - freemarker

Question

Hi I have a question in liferay 7.4 ,
I am using assetRenderer Class to build a freemarker template.
https://docs.liferay.com/portal/7.4-latest/javadocs/portal-kernel/com/liferay/dynamic/data/mapping/kernel/DDMFormFieldValue.html
My problem is I cannot get the url from the featuredImage field which is an image field in a structure, I get a whole value which is a string, I would like to have another way.
<#function getFieldData ddmFormFieldValues fieldReference>
<#list ddmFormFieldValues as ddmFormFieldValue>
<#if ddmFormFieldValue.getDDMFormField().getFieldReference()==fieldReference>
<#if (ddmFormFieldValue)??>
<#assign value=ddmFormFieldValue />
<#return value />
<#else>
<#return null />
</#if>
</#if>
</#list>
<#return null />
</#function>
<#assign ddmFormValuesReader = assetRenderer.getDDMFormValuesReader() />
<#assign ddmFormFieldValues =
ddmFormValuesReader.getDDMFormValues().getDDMFormFieldValues()/>
<#assign newsImage = getFieldData(ddmFormFieldValues, 'featuredImage') />
${newsImage.getValue().getString(locale)}
The result will be a string like this :
{"extension":"jpg","fileEntryId":"631318","groupId":"630625","title":"Dino-bakgrund.png","type":"document","url":"\/documents\/630625\/0\/Dino-bakgrund.png.jpg\/ecffe3b3-333e-3da3-6bb4-732da3d60947?t=1557132929823&imagePreview=1","uuid":"ecffe3b3-333e-3da3-6bb4-732da3d60947"}
Is there a way to get the property directly, since I get a string here ?
I can convert the String to Json and get the result, but this is not a good way something like this :
<#assign newsImage_map = jsonFactoryUtil.createJSONObject(newsImage) />
<#if (newsImage_map.url)?? >
<#assign newsImageUrl = newsImage_map.url />
${newsImageUrl }
</#if>
Is there away that I do not covert to JSON ?