Convert OperationName to an extensible enum.

jena-fuseki2/jena-fuseki-core/src/main/java/org/apache/jena/fuseki/mgt/ActionStats.java

@@ -108,8 +108,8 @@ private static void statsDataset(JsonBuilder builder, DataAccessPoint access) {
                 builder.startObject() ;
 
                 operationCounters(builder, endpoint);
-                builder.key(JsonConst.operation).value(operName.name()) ;
-                builder.key(JsonConst.description).value(operName.getDescription()) ;
+                builder.key(JsonConst.operation).value(operName.getName()) ;
+                builder.key(JsonConst.description).value(operName.getName()) ;
 
                 builder.finishObject() ;
             }

jena-fuseki2/jena-fuseki-core/src/main/java/org/apache/jena/fuseki/mgt/JsonDescription.java

@@ -58,8 +58,8 @@ public static void describe(JsonBuilder builder, DataAccessPoint access) {
     private static void describe(JsonBuilder builder, OperationName opName, List<Endpoint> endpoints) {
         builder.startObject() ;
 
-        builder.key(JsonConst.srvType).value(opName.name()) ;
-        builder.key(JsonConst.srvDescription).value(opName.getDescription()) ;
+        builder.key(JsonConst.srvType).value(opName.getName()) ;
+        builder.key(JsonConst.srvDescription).value(opName.getName()) ;
 
         builder.key(JsonConst.srvEndpoints) ;
         builder.startArray() ;

jena-fuseki2/jena-fuseki-core/src/main/java/org/apache/jena/fuseki/server/OperationName.java

@@ -18,20 +18,68 @@
 
 package org.apache.jena.fuseki.server;
 
-public enum OperationName {
-    // Fixed names give the codebase some resilience.
-    Query("SPARQL Query"),
-    Update("SPARQL Update"),
-    Upload("File Upload"),
-    GSP_RW("Graph Store Protocol"),
-    GSP_R("Graph Store Protocol (Read)"),
-    Quads_RW("HTTP Quads"),
-    Quads_R("HTTP Quads (Read)")
-    ;
-
-    private final String description ;
-    private OperationName(String description) { this.description = description ; }
-    public String getDescription() { return description ; }
+import java.util.HashMap;
+import java.util.Map;
+
+/** 
+ * Names (symbols) for operations.
+ * An {@code OperationName} is not related to the service name used to invoke the operation.
+ * That is determined by the {@link Endpoint}. 
+ */
+public class OperationName {
+
+    // Create intern'ed symbols. 
+    static private Map<String, OperationName> registered = new HashMap<>();
+
+    /**
+     * Create an intern'ed {@code OperationName}. That is, if the object has already been
+     * created, return the original. There is only ever one object for a given name.
+     * (It is an extensible enum without subclassing).
+     */
+    static public OperationName register(String name) {
+        return registered.computeIfAbsent(name, (n)->new OperationName(n));
+    }
+
+    public static OperationName Query    = register("SPARQL Query");
+    public static OperationName Update   = register("SPARQL Update");
+    public static OperationName Upload   = register("File Upload");
+    public static OperationName GSP_RW   = register("Graph Store Protocol");
+    public static OperationName GSP_R    = register("Graph Store Protocol (Read)");
+    public static OperationName Quads_RW = register("HTTP Quads");
+    public static OperationName Quads_R  = register("HTTP Quads (Read)");
+
+    private final String name ;
+    private OperationName(String name) { this.name = name ; }
+
+    public String getName() { return name ; }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((name == null) ? 0 : name.hashCode());
+        return result;
+    }
+
+    // Could be this == obj
+    // because we intern'ed the object
+
+    @Override
+    public boolean equals(Object obj) {
+        if ( this == obj )
+            return true;
+        if ( obj == null )
+            return false;
+        if ( getClass() != obj.getClass() )
+            return false;
+        OperationName other = (OperationName)obj;
+        if ( name == null ) {
+            if ( other.name != null )
+                return false;
+        } else if ( !name.equals(other.name) )
+            return false;
+        return true;
+    }
 
 }