Merge pull request #5621 from QualitativeDataRepository/IQSS-4894-Open_Graph_metadata

use dataset thumbnail if available

Author: sekmiller

doc/release-notes/5621_dataset image in header.md

@@ -0,0 +1 @@
+Dataverse will use the Dataset thumbnail, if one is defined, rather than the generic Dataverse logo in the Open Graph metadata header. This means the image will be seen when, for example, the dataset is referenced in Facebook.

src/main/webapp/dataset.xhtml

@@ -86,7 +86,7 @@
                     <meta property="og:title" content="#{DatasetPage.title}" />
                     <meta property="og:type" content="article" />
                     <meta property="og:url" content="#{DatasetPage.dataverseSiteUrl}/dataset.xhtml?persistentId=#{dataset.globalId}" />
-                    <meta property="og:image" content="#{DatasetPage.dataverseSiteUrl.concat(resource['images/dataverse-icon-1200.png'])}" />
+                    <meta property="og:image" content="#{DatasetPage.dataset.getDatasetThumbnail(ImageThumbConverter.DEFAULT_PREVIEW_SIZE) == null ? DatasetPage.dataverseSiteUrl.concat(resource['images/dataverse-icon-1200.png']): DatasetPage.dataverseSiteUrl.concat('/api/datasets/:persistentId/thumbnail?persistentId=').concat(DatasetPage.dataset.getGlobalId().asString())}" />
                     <meta property="og:site_name" content="#{DatasetPage.publisher}" />
                     <meta property="og:description" content="#{(DatasetPage.description.length()>150 ? DatasetPage.description.substring(0,147).concat('...') : DatasetPage.description)}" />
                     <ui:repeat var="author" value="#{DatasetPage.datasetAuthors}">