upgrade dependencies

spring-cloud/spring-cloud-eureka/pom.xml

@@ -25,6 +25,8 @@
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
+        <spring-boot-maven-plugin.version>1.4.2.RELEASE</spring-boot-maven-plugin.version>
     </properties>
 
     <build>
@@ -33,7 +35,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-compiler-plugin</artifactId>
-                    <version>3.5.1</version>
+                    <version>${maven-compiler-plugin.version}</version>
                     <configuration>
                         <source>1.8</source>
                         <target>1.8</target>
@@ -42,7 +44,7 @@
                 <plugin>
                     <groupId>org.springframework.boot</groupId>
                     <artifactId>spring-boot-maven-plugin</artifactId>
-                    <version>1.4.0.RELEASE</version>
+                    <version>${spring-boot-maven-plugin.version}</version>
                 </plugin>
             </plugins>
         </pluginManagement>