Added failing test and fix or issue #646

src/main/java/com/fasterxml/jackson/dataformat/xml/util/TypeUtil.java

@@ -11,7 +11,7 @@ public class TypeUtil
     public static boolean isIndexedType(JavaType type)
     {
         Class<?> cls = type.getRawClass();
-        if (type.isContainerType() || type.isIterationType()) {
+        if (type.isContainerType() || type.isIterationType() || cls == Iterable.class) {
             // One special case; byte[] will be serialized as base64-encoded String, not real array, so:
             // (actually, ditto for char[]; thought to be a String)
             if (cls == byte[].class || cls == char[].class) {

src/test/java/com/fasterxml/jackson/dataformat/xml/failing/IterableCollectionBuilder646Test.java

@@ -0,0 +1,88 @@
+package com.fasterxml.jackson.dataformat.xml.failing;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.fasterxml.jackson.dataformat.xml.XmlMapper;
+import com.fasterxml.jackson.dataformat.xml.XmlTestBase;
+import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlElementWrapper;
+import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlRootElement;
+
+public class IterableCollectionBuilder646Test extends XmlTestBase {
+
+	@JsonDeserialize(builder = Parent.Builder.class)
+	@JacksonXmlRootElement(localName = "parent")
+	static class Parent {
+		private final List<Child> children;
+
+		private Parent(List<Child> children) {
+			this.children = children;
+		}
+
+		@JsonProperty("child")
+		@JacksonXmlElementWrapper(useWrapping = false)
+		public List<Child> getChildren() {
+			return children;
+		}
+
+		static class Builder {
+			private final List<Child> children = new ArrayList<>();
+
+			@JsonProperty("child")
+			@JacksonXmlElementWrapper(useWrapping = false)
+			public Builder children(Iterable<Child> children) {
+				for (Child c : children) {
+					this.children.add(c);
+				}
+				return this;
+			}
+
+			public Parent build() {
+				return new Parent(children);
+			}
+		}
+	}
+
+	@JsonDeserialize(builder = Child.Builder.class)
+	@JacksonXmlRootElement(localName = "child")
+	static class Child {
+		private final String id;
+
+		public Child(String id) {
+			this.id = id;
+		}
+
+		@JsonProperty("id")
+		public String getId() {
+			return id;
+		}
+
+		static class Builder {
+			private String id;
+
+			@JsonProperty("id")
+			public Builder id(String id) {
+				this.id = id;
+				return this;
+			}
+
+			public Child build() {
+				return new Child(id);
+			}
+		}
+	}
+
+	// -- Test Methods --//
+	private final XmlMapper MAPPER = newMapper();
+
+	public void testIssue646() throws Exception {
+		final String XML = "<parent><child><id>1</id></child></parent>";
+		Parent parent = MAPPER.readValue(XML, Parent.class);
+		assertNotNull(parent);
+		assertNotNull(parent.getChildren());
+		assertEquals(1, parent.getChildren().size());
+
+	}
+}