LUCENE-7360: Explanation.toHtml() is deprecated

lucene/CHANGES.txt

@@ -81,6 +81,8 @@ Other
 
 * LUCENE-7346: Update forbiddenapis to version 2.2.
   (Uwe Schindler)
+
+* LUCENE-7360: Explanation.toHtml() is deprecated. (Alan Woodward)
   
 ======================= Lucene 6.1.0 =======================
 

lucene/core/src/java/org/apache/lucene/search/Explanation.java

@@ -123,6 +123,7 @@ public final class Explanation {
 
 
   /** Render an explanation as HTML. */
+  @Deprecated
   public String toHtml() {
     StringBuilder buffer = new StringBuilder();
     buffer.append("<ul>\n");

solr/core/src/java/org/apache/solr/response/transform/ExplainAugmenterFactory.java

@@ -70,6 +70,26 @@ public class ExplainAugmenterFactory extends TransformerFactory
     return new ExplainAugmenter( field, style );
   }
 
+  /** Render an explanation as HTML. */
+  public static String toHtml(Explanation explanation) {
+    StringBuilder buffer = new StringBuilder();
+    buffer.append("<ul>\n");
+
+    buffer.append("<li>");
+    buffer.append(explanation.getValue()).append(" = ").append(explanation.getDescription());
+    buffer.append("<br />\n");
+
+    Explanation[] details = explanation.getDetails();
+    for (int i = 0 ; i < details.length; i++) {
+      buffer.append(toHtml(details[i]));
+    }
+
+    buffer.append("</li>\n");
+    buffer.append("</ul>\n");
+
+    return buffer.toString();
+  }
+
   static class ExplainAugmenter extends DocTransformer {
     final String name;
     final Style style;
@@ -95,7 +115,7 @@ public class ExplainAugmenterFactory extends TransformerFactory
             doc.setField( name, SolrPluginUtils.explanationToNamedList(exp) );
           }
           else if( style == Style.html ) {
-            doc.setField( name, exp.toHtml() );
+            doc.setField( name, toHtml(exp));
           }
           else {
             doc.setField( name, exp.toString() );