gh-2669: Added new aggregation function endpoints

rest-api/core-rest/src/main/java/uk/gov/gchq/gaffer/rest/service/v2/GraphConfigurationServiceV2.java

@@ -39,6 +39,7 @@
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.function.BinaryOperator;
 import java.util.function.Function;
 import java.util.function.Predicate;
 
@@ -83,6 +84,13 @@ public Response getFilterFunction() {
                 .build();
     }
 
+    @Override
+    public Response getAggregationFunctions() {
+        return Response.ok(ReflectionUtil.getSubTypes(BinaryOperator.class))
+                .header(GAFFER_MEDIA_TYPE_HEADER, GAFFER_MEDIA_TYPE)
+                .build();
+    }
+
     @SuppressFBWarnings(value = "REC_CATCH_EXCEPTION", justification = "Need to wrap all runtime exceptions before they are given to the user")
     @Override
     public Response getFilterFunction(final String inputClass) {

rest-api/core-rest/src/main/java/uk/gov/gchq/gaffer/rest/service/v2/IGraphConfigurationServiceV2.java

@@ -110,6 +110,20 @@ public interface IGraphConfigurationServiceV2 {
             @ApiResponse(code = 500, message = INTERNAL_SERVER_ERROR)})
     Response getTransformFunctions();
 
+    @GET
+    @Path("/aggregationFunctions")
+    @ApiOperation(value = "Gets available aggregation functions",
+            notes = "Returns a list of the fully qualified classpaths of all available aggregation functions, in no particular order.",
+            response = String.class,
+            responseContainer = "list",
+            produces = APPLICATION_JSON,
+            responseHeaders = {
+                    @ResponseHeader(name = GAFFER_MEDIA_TYPE_HEADER, description = GAFFER_MEDIA_TYPE_HEADER_DESCRIPTION)
+            })
+    @ApiResponses(value = {@ApiResponse(code = 200, message = OK),
+            @ApiResponse(code = 500, message = INTERNAL_SERVER_ERROR)})
+    Response getAggregationFunctions();
+
     @GET
     @Path("/elementGenerators")
     @ApiOperation(value = "Gets available element generators",

rest-api/core-rest/src/test/java/uk/gov/gchq/gaffer/rest/service/v2/GraphConfigurationServiceV2Test.java

@@ -266,6 +266,15 @@ public void shouldGetTransformFunctions() {
         assertFalse(classes.isEmpty());
     }
 
+    @Test
+    public void shouldGetAggregationFunctions() {
+        // When
+        final Set<Class> classes = (Set<Class>) service.getAggregationFunctions().getEntity();
+
+        // Then
+        assertFalse(classes.isEmpty());
+    }
+
     @Test
     public void shouldGetElementGenerators() {
         // When

rest-api/spring-rest/src/main/java/uk/gov/gchq/gaffer/rest/controller/GraphConfigurationController.java

@@ -36,6 +36,7 @@
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
+import java.util.function.BinaryOperator;
 import java.util.function.Function;
 import java.util.function.Predicate;
 
@@ -140,4 +141,9 @@ public Set<StoreTrait> getStoreTraits() {
     public Set<Class> getTransformFunctions() {
         return ReflectionUtil.getSubTypes(Function.class);
     }
+
+    @Override
+    public Set<Class> getAggregationFunctions() {
+        return ReflectionUtil.getSubTypes(BinaryOperator.class);
+    }
 }

rest-api/spring-rest/src/main/java/uk/gov/gchq/gaffer/rest/controller/IGraphConfigurationController.java

@@ -160,4 +160,16 @@ public interface IGraphConfigurationController {
             responseContainer = "Set"
     )
     Set<Class> getTransformFunctions();
+
+    @RequestMapping(
+            path = "/aggregationFunctions",
+            method = GET,
+            produces = APPLICATION_JSON_VALUE
+    )
+    @ApiOperation(
+            value = "Gets the available aggregation functions",
+            response = Class.class,
+            responseContainer = "Set"
+    )
+    Set<Class> getAggregationFunctions();
 }

rest-api/spring-rest/src/test/java/uk/gov/gchq/gaffer/rest/controller/GraphConfigurationControllerTest.java

@@ -284,6 +284,18 @@ public void shouldGetTransformFunctions() {
         assertFalse(classes.isEmpty());
     }
 
+    @Test
+    public void shouldGetAggregationFunctions() {
+        // Given
+        GraphConfigurationController controller = new GraphConfigurationController(graphFactory);
+
+        // When
+        final Set<Class> classes = controller.getAggregationFunctions();
+
+        // Then
+        assertFalse(classes.isEmpty());
+    }
+
     @Test
     public void shouldGetElementGenerators() {
         // Given