Fix some maven warnings

spring-boot-parent/pom.xml

@@ -279,7 +279,7 @@
 											[1.3.1,)
 										</versionRange>
 										<goals>
-											<goal>enforce-once</goal>
+											<goal>enforce</goal>
 										</goals>
 									</pluginExecutionFilter>
 									<action>
@@ -341,7 +341,7 @@
 					<execution>
 						<id>enforce-rules</id>
 						<goals>
-							<goal>enforce-once</goal>
+							<goal>enforce</goal>
 						</goals>
 						<configuration>
 							<rules>

spring-boot-tools/spring-boot-loader/src/it/executable-dir/pom.xml

@@ -6,6 +6,9 @@
 	<artifactId>executable-dir</artifactId>
 	<version>0.0.1.BUILD-SNAPSHOT</version>
 	<packaging>jar</packaging>
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
 	<build>
 		<plugins>
 			<plugin>

spring-boot-tools/spring-boot-loader/src/it/executable-jar/pom.xml

@@ -6,6 +6,9 @@
 	<artifactId>executable-jar</artifactId>
 	<version>0.0.1.BUILD-SNAPSHOT</version>
 	<packaging>jar</packaging>
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
 	<build>
 		<plugins>
 			<plugin>

spring-boot-tools/spring-boot-loader/src/it/executable-war/pom.xml

@@ -6,6 +6,9 @@
 	<artifactId>executable-war</artifactId>
 	<version>0.0.1.BUILD-SNAPSHOT</version>
 	<packaging>war</packaging>
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
 	<build>
 		<plugins>
 			<plugin>

spring-boot-tools/spring-boot-maven-plugin/src/it/jar/pom.xml

@@ -6,6 +6,9 @@
 	<artifactId>jar</artifactId>
 	<version>0.0.1.BUILD-SNAPSHOT</version>
 	<packaging>jar</packaging>
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+	</properties>
 	<build>
 		<plugins>
 			<plugin>

spring-boot-tools/spring-boot-maven-plugin/src/it/prop/pom.xml

@@ -6,6 +6,9 @@
 	<artifactId>jar</artifactId>
 	<version>0.0.1.BUILD-SNAPSHOT</version>
 	<packaging>jar</packaging>
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+	</properties>
 	<build>
 		<plugins>
 			<plugin>

spring-boot-tools/spring-boot-maven-plugin/src/it/run/pom.xml

@@ -6,6 +6,9 @@
 	<artifactId>run</artifactId>
 	<version>0.0.1.BUILD-SNAPSHOT</version>
 	<packaging>jar</packaging>
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+	</properties>
 	<build>
 		<plugins>
 			<plugin>

spring-boot-tools/spring-boot-maven-plugin/src/it/war/pom.xml

@@ -6,6 +6,9 @@
 	<artifactId>war</artifactId>
 	<version>0.0.1.BUILD-SNAPSHOT</version>
 	<packaging>war</packaging>
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+	</properties>
 	<build>
 		<plugins>
 			<plugin>