Fix logic error in BeanPath relating to lists of beans

There was a counting error affecting bean paths like
nested[0].foo[1].bar (needed to reset a counter to 0).
Tests seem fine and I added a couple of new ones for that
use case.

Fixes gh-3065

spring-boot/src/main/java/org/springframework/boot/bind/RelaxedDataBinder.java

@@ -461,12 +461,11 @@ public class RelaxedDataBinder extends DataBinder {
 		}
 
 		private String extractIndexedPaths(String path, List<PathNode> nodes) {
-			int begin = 0;
 			int startRef = path.indexOf("[");
 			String current = path;
 			while (startRef >= 0) {
-				if (startRef > begin) {
-					nodes.addAll(splitPath(current.substring(begin, startRef)));
+				if (startRef > 0) {
+					nodes.addAll(splitPath(current.substring(0, startRef)));
 				}
 				int endRef = current.indexOf("]", startRef);
 				if (endRef > 0) {
@@ -478,8 +477,7 @@ public class RelaxedDataBinder extends DataBinder {
 						nodes.add(new MapIndexNode(sub));
 					}
 				}
-				begin = endRef + 1;
-				current = current.substring(begin);
+				current = current.substring(endRef + 1);
 				startRef = current.indexOf("[");
 			}
 			return current;

spring-boot/src/test/java/org/springframework/boot/bind/BindingPreparationTests.java

@@ -62,6 +62,28 @@ public class BindingPreparationTests {
 		assertNotNull(wrapper.getPropertyValue("nested[foo]"));
 	}
 
+	@Test
+	public void testListOfBeansWithList() throws Exception {
+		TargetWithNestedListOfBeansWithList target = new TargetWithNestedListOfBeansWithList();
+		BeanWrapperImpl wrapper = new BeanWrapperImpl(target);
+		wrapper.setAutoGrowNestedPaths(true);
+		RelaxedDataBinder binder = new RelaxedDataBinder(target);
+		binder.normalizePath(wrapper, "nested[0].list[1]");
+		assertNotNull(wrapper.getPropertyValue("nested"));
+		assertNotNull(wrapper.getPropertyValue("nested[0].list[1]"));
+	}
+
+	@Test
+	public void testListOfBeansWithListAndNoPeriod() throws Exception {
+		TargetWithNestedListOfBeansWithList target = new TargetWithNestedListOfBeansWithList();
+		BeanWrapperImpl wrapper = new BeanWrapperImpl(target);
+		wrapper.setAutoGrowNestedPaths(true);
+		RelaxedDataBinder binder = new RelaxedDataBinder(target);
+		binder.normalizePath(wrapper, "nested[0]list[1]");
+		assertNotNull(wrapper.getPropertyValue("nested"));
+		assertNotNull(wrapper.getPropertyValue("nested[0].list[1]"));
+	}
+
 	@Test
 	public void testAutoGrowWithFuzzyNameCapitals() throws Exception {
 		TargetWithNestedMap target = new TargetWithNestedMap();
@@ -259,6 +281,31 @@ public class BindingPreparationTests {
 		}
 	}
 
+	public static class TargetWithNestedListOfBeansWithList {
+		private List<TargetWithList> nested;
+
+		public List<TargetWithList> getNested() {
+			return this.nested;
+		}
+
+		public void setNested(List<TargetWithList> nested) {
+			this.nested = nested;
+		}
+	}
+
+	public static class TargetWithList {
+		private List<VanillaTarget> list;
+
+		public List<VanillaTarget> getList() {
+			return this.list;
+		}
+
+		public void setList(List<VanillaTarget> list) {
+			this.list = list;
+		}
+
+	}
+
 	public static class TargetWithNestedMapOfBean {
 		private Map<String, VanillaTarget> nested;
 

spring-boot/src/test/java/org/springframework/boot/bind/RelaxedDataBinderTests.java

@@ -231,6 +231,20 @@ public class RelaxedDataBinderTests {
 		assertEquals("[bar, foo]", target.getNested().toString());
 	}
 
+	@Test
+	public void testBindNestedListOfBean() throws Exception {
+		TargetWithNestedListOfBean target = new TargetWithNestedListOfBean();
+		bind(target, "nested[0].foo: bar\nnested[1].foo: foo");
+		assertEquals("bar", target.getNested().get(0).getFoo());
+	}
+
+	@Test
+	public void testBindNestedListOfBeanWithList() throws Exception {
+		TargetWithNestedListOfBeanWithList target = new TargetWithNestedListOfBeanWithList();
+		bind(target, "nested[0].nested[0].foo: bar\nnested[1].nested[0].foo: foo");
+		assertEquals("bar", target.getNested().get(0).getNested().get(0).getFoo());
+	}
+
 	@Test
 	public void testBindNestedListCommaDelimitedOnly() throws Exception {
 		TargetWithNestedList target = new TargetWithNestedList();
@@ -764,6 +778,34 @@ public class RelaxedDataBinderTests {
 
 	}
 
+	public static class TargetWithNestedListOfBean {
+
+		private List<VanillaTarget> nested;
+
+		public List<VanillaTarget> getNested() {
+			return this.nested;
+		}
+
+		public void setNested(List<VanillaTarget> nested) {
+			this.nested = nested;
+		}
+
+	}
+
+	public static class TargetWithNestedListOfBeanWithList {
+
+		private List<TargetWithNestedListOfBean> nested;
+
+		public List<TargetWithNestedListOfBean> getNested() {
+			return this.nested;
+		}
+
+		public void setNested(List<TargetWithNestedListOfBean> nested) {
+			this.nested = nested;
+		}
+
+	}
+
 	public static class TargetWithReadOnlyNestedList {
 
 		private final List<String> nested = new ArrayList<String>();