Properly identify accessor methods

This commit fixes the binder so that it property identifies JavaBean
accessors. Previously an accessor named `get` or `is` was identified.
Similarly, a setter named `set` was identified.

Closes gh-12363

Author: snicoll

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/JavaBeanBinder.java

@@ -126,17 +126,17 @@ private boolean isCandidate(Method method) {
 		private void addMethod(Method method) {
 			String name = method.getName();
 			int parameterCount = method.getParameterCount();
-			if (name.startsWith("get") && parameterCount == 0) {
+			if (name.startsWith("get") && parameterCount == 0 && name.length() > 3) {
 				name = Introspector.decapitalize(name.substring(3));
 				this.properties.computeIfAbsent(name, this::getBeanProperty)
 						.addGetter(method);
 			}
-			else if (name.startsWith("is") && parameterCount == 0) {
+			else if (name.startsWith("is") && parameterCount == 0 && name.length() > 2) {
 				name = Introspector.decapitalize(name.substring(2));
 				this.properties.computeIfAbsent(name, this::getBeanProperty)
 						.addGetter(method);
 			}
-			else if (name.startsWith("set") && parameterCount == 1) {
+			else if (name.startsWith("set") && parameterCount == 1 && name.length() > 3) {
 				name = Introspector.decapitalize(name.substring(3));
 				this.properties.computeIfAbsent(name, this::getBeanProperty)
 						.addSetter(method);

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/JavaBeanBinderTests.java

@@ -476,6 +476,16 @@ public void bindWhenValueIsConvertedWithPropertyEditorShouldBind() {
 		assertThat(bean.getValue()).isEqualTo(RuntimeException.class);
 	}
 
+	@Test
+	public void bindToClassShouldIgnoreInvalidAccessors() {
+		MockConfigurationPropertySource source = new MockConfigurationPropertySource();
+		source.put("foo.name", "something");
+		this.sources.add(source);
+		ExampleWithInvalidAccessors bean = this.binder
+				.bind("foo", Bindable.of(ExampleWithInvalidAccessors.class)).get();
+		assertThat(bean.getName()).isEqualTo("something");
+	}
+
 	public static class ExampleValueBean {
 
 		private int intValue;
@@ -813,6 +823,28 @@ public void setSelf(ExampleWithSelfReference self) {
 
 	}
 
+	public static class ExampleWithInvalidAccessors {
+
+		private String name;
+
+		public String getName() {
+			return this.name;
+		}
+
+		public void setName(String name) {
+			this.name = name;
+		}
+
+		public String get() {
+			throw new IllegalArgumentException("should not be invoked");
+		}
+
+		public boolean is() {
+			throw new IllegalArgumentException("should not be invoked");
+		}
+
+	}
+
 	public enum ExampleEnum {
 
 		FOO_BAR,