Defer support on ENFs

src/main/java/graphql/Directives.java

@@ -1,6 +1,7 @@
 package graphql;
 
 
+import graphql.language.BooleanValue;
 import graphql.language.Description;
 import graphql.language.DirectiveDefinition;
 import graphql.language.StringValue;
@@ -33,14 +34,14 @@ public class Directives {
     private static final String SPECIFIED_BY = "specifiedBy";
     private static final String DEPRECATED = "deprecated";
     private static final String ONE_OF = "oneOf";
+    private static final String DEFER = "defer";
 
     public static final String NO_LONGER_SUPPORTED = "No longer supported";
     public static final DirectiveDefinition DEPRECATED_DIRECTIVE_DEFINITION;
     public static final DirectiveDefinition SPECIFIED_BY_DIRECTIVE_DEFINITION;
     @ExperimentalApi
     public static final DirectiveDefinition ONE_OF_DIRECTIVE_DEFINITION;
 
-
     static {
         DEPRECATED_DIRECTIVE_DEFINITION = DirectiveDefinition.newDirectiveDefinition()
                 .name(DEPRECATED)
@@ -77,6 +78,28 @@ public class Directives {
                 .build();
     }
 
+    /**
+     * The @defer directive can be used to defer sending data for a fragment until later in the query.
+     * This is an opt-in directive that is not available unless it is explicitly put into the schema.
+     */
+    @ExperimentalApi
+    public static final GraphQLDirective DeferDirective = GraphQLDirective.newDirective()
+            .name("defer")
+            .description("This directive allows results to be deferred during execution")
+            .validLocations(FRAGMENT_SPREAD, INLINE_FRAGMENT)
+            .argument(newArgument()
+                    .name("if")
+                    .type(nonNull(GraphQLBoolean))
+                    .description("Deferred behaviour is controlled by this argument")
+                    .defaultValueLiteral(BooleanValue.newBooleanValue(true).build())
+            )
+            .argument(newArgument()
+                    .name("label")
+                    .type(GraphQLString)
+                    .description("A unique label that represents the fragment being deferred")
+            )
+            .build();
+
     public static final GraphQLDirective IncludeDirective = GraphQLDirective.newDirective()
             .name("include")
             .description("Directs the executor to include this field or fragment only when the `if` argument is true")

src/main/java/graphql/ExperimentalApi.java

@@ -12,9 +12,9 @@
 
 /**
  * This represents code that the graphql-java project considers experimental API and while our intention is that it will
- * progress to be {@link PublicApi}, its existence, signature of behavior may change between releases.
- *
- * In general unnecessary changes will be avoided but you should not depend on experimental classes being stable
+ * progress to be {@link PublicApi}, its existence, signature or behavior may change between releases.
+ * <p>
+ * In general unnecessary changes will be avoided, but you should not depend on experimental classes being stable.
  */
 @Retention(RetentionPolicy.RUNTIME)
 @Target(value = {CONSTRUCTOR, METHOD, TYPE, FIELD})

src/main/java/graphql/execution/FieldCollector.java

@@ -25,7 +25,7 @@
 
 /**
  * A field collector can iterate over field selection sets and build out the sub fields that have been selected,
- * expanding named and inline fragments as it goes.s
+ * expanding named and inline fragments as it goes.
  */
 @Internal
 public class FieldCollector {

src/main/java/graphql/normalized/ExecutableNormalizedField.java

@@ -63,7 +63,6 @@ public class ExecutableNormalizedField {
     private final String fieldName;
     private final int level;
 
-
     private ExecutableNormalizedField(Builder builder) {
         this.alias = builder.alias;
         this.resolvedArguments = builder.resolvedArguments;
@@ -261,7 +260,6 @@ public void clearChildren() {
      * WARNING: This is not always the key in the execution result, because of possible field aliases.
      *
      * @return the name of this {@link ExecutableNormalizedField}
-     *
      * @see #getResultKey()
      * @see #getAlias()
      */
@@ -271,7 +269,6 @@ public String getName() {
 
     /**
      * @return the same value as {@link #getName()}
-     *
      * @see #getResultKey()
      * @see #getAlias()
      */
@@ -284,7 +281,6 @@ public String getFieldName() {
      * This is either a field alias or the value of {@link #getName()}
      *
      * @return the result key for this {@link ExecutableNormalizedField}.
-     *
      * @see #getName()
      */
     public String getResultKey() {
@@ -296,7 +292,6 @@ public String getResultKey() {
 
     /**
      * @return the field alias used or null if there is none
-     *
      * @see #getResultKey()
      * @see #getName()
      */
@@ -315,7 +310,6 @@ public ImmutableList<Argument> getAstArguments() {
      * Returns an argument value as a {@link NormalizedInputValue} which contains its type name and its current value
      *
      * @param name the name of the argument
-     *
      * @return an argument value
      */
     public NormalizedInputValue getNormalizedArgument(String name) {
@@ -364,7 +358,6 @@ public String getSingleObjectTypeName() {
         return objectTypeNames.iterator().next();
     }
 
-
     /**
      * @return a helper method show field details
      */
@@ -414,7 +407,6 @@ public List<ExecutableNormalizedField> getChildren() {
      * Returns the list of child fields that would have the same result key
      *
      * @param resultKey the result key to check
-     *
      * @return a list of all direct {@link ExecutableNormalizedField} children with the specified result key
      */
     public List<ExecutableNormalizedField> getChildrenWithSameResultKey(String resultKey) {
@@ -435,7 +427,6 @@ public List<ExecutableNormalizedField> getChildren(int includingRelativeLevel) {
      * This returns the child fields that can be used if the object is of the specified object type
      *
      * @param objectTypeName the object type
-     *
      * @return a list of child fields that would apply to that object type
      */
     public List<ExecutableNormalizedField> getChildren(String objectTypeName) {
@@ -568,7 +559,6 @@ public static Builder newNormalizedField() {
      * Allows this {@link ExecutableNormalizedField} to be transformed via a {@link Builder} consumer callback
      *
      * @param builderConsumer the consumer given a builder
-     *
      * @return a new transformed {@link ExecutableNormalizedField}
      */
     public ExecutableNormalizedField transform(Consumer<Builder> builderConsumer) {

src/main/java/graphql/normalized/ExecutableNormalizedOperation.java

@@ -2,12 +2,14 @@
 
 import com.google.common.collect.ImmutableListMultimap;
 import graphql.Assert;
+import graphql.ExperimentalApi;
 import graphql.PublicApi;
 import graphql.execution.MergedField;
 import graphql.execution.ResultPath;
 import graphql.execution.directives.QueryDirectives;
 import graphql.language.Field;
 import graphql.language.OperationDefinition;
+import graphql.normalized.incremental.DeferExecution;
 import graphql.schema.FieldCoordinates;
 import graphql.schema.GraphQLFieldsContainer;
 
@@ -30,6 +32,7 @@ public class ExecutableNormalizedOperation {
     private final ImmutableListMultimap<Field, ExecutableNormalizedField> fieldToNormalizedField;
     private final Map<ExecutableNormalizedField, MergedField> normalizedFieldToMergedField;
     private final Map<ExecutableNormalizedField, QueryDirectives> normalizedFieldToQueryDirectives;
+    private final ImmutableListMultimap<ExecutableNormalizedField, DeferExecution> normalizedFieldToDeferExecution;
     private final ImmutableListMultimap<FieldCoordinates, ExecutableNormalizedField> coordinatesToNormalizedFields;
 
     public ExecutableNormalizedOperation(
@@ -39,7 +42,8 @@ public ExecutableNormalizedOperation(
             ImmutableListMultimap<Field, ExecutableNormalizedField> fieldToNormalizedField,
             Map<ExecutableNormalizedField, MergedField> normalizedFieldToMergedField,
             Map<ExecutableNormalizedField, QueryDirectives> normalizedFieldToQueryDirectives,
-            ImmutableListMultimap<FieldCoordinates, ExecutableNormalizedField> coordinatesToNormalizedFields
+            ImmutableListMultimap<FieldCoordinates, ExecutableNormalizedField> coordinatesToNormalizedFields,
+            ImmutableListMultimap<ExecutableNormalizedField, DeferExecution> normalizedFieldToDeferExecution
     ) {
         this.operation = operation;
         this.operationName = operationName;
@@ -48,6 +52,7 @@ public ExecutableNormalizedOperation(
         this.normalizedFieldToMergedField = normalizedFieldToMergedField;
         this.normalizedFieldToQueryDirectives = normalizedFieldToQueryDirectives;
         this.coordinatesToNormalizedFields = coordinatesToNormalizedFields;
+        this.normalizedFieldToDeferExecution = normalizedFieldToDeferExecution;
     }
 
     /**
@@ -126,6 +131,15 @@ public Map<ExecutableNormalizedField, QueryDirectives> getNormalizedFieldToQuery
 
     }
 
+    /**
+     * @return a map of {@link ExecutableNormalizedField} to  its {@link DeferExecution}
+     */
+    @ExperimentalApi
+    public ImmutableListMultimap<ExecutableNormalizedField, DeferExecution> getNormalizedFieldToDeferExecution() {
+        return normalizedFieldToDeferExecution;
+    }
+
+
     /**
      * This looks up the {@link QueryDirectives} associated with the given {@link ExecutableNormalizedField}
      *