Removed redundant entries from POM files

Polished POM files to remove redundant entries that were causing warnings in the IDE. Some notable changes are:
- Removed spring-boot.version from sample project as they inherit it from the parent
- Removed versioning for maven-jar-plugin (was 3.0) from multiple project so it relies on the managed version
- Removed java.version from all spring-cloud-function-* modules as they inherit the one from parent.

Addressed PR comments
- removed references to maven-jar-plugin

spring-cloud-function-compiler/pom.xml

@@ -13,15 +13,10 @@
 		<version>1.0.0.BUILD-SNAPSHOT</version>
 	</parent>
 
-	<properties>
-		<java.version>1.8</java.version>
-	</properties>
-
 	<dependencies>
 		<dependency>
 			<groupId>io.projectreactor</groupId>
 			<artifactId>reactor-core</artifactId>
-			<version>3.0.4.RELEASE</version>
 		</dependency>
 		<dependency>
 			<groupId>org.eclipse.jdt.core.compiler</groupId>

spring-cloud-function-context/pom.xml

@@ -15,7 +15,6 @@
 	</parent>
 
 	<properties>
-		<java.version>1.8</java.version>
 		<spring-cloud-function.version>1.0.0.BUILD-SNAPSHOT</spring-cloud-function.version>
 	</properties>
 
@@ -35,15 +34,4 @@
 			<optional>true</optional>
 		</dependency>
 	</dependencies>
-
-	<build>
-		<plugins>
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-jar-plugin</artifactId>
-				<version>3.0.0</version>
-			</plugin>
-		</plugins>
-	</build>
-
 </project>

spring-cloud-function-core/pom.xml

@@ -13,10 +13,6 @@
 		<version>1.0.0.BUILD-SNAPSHOT</version>
 	</parent>
 
-	<properties>
-		<java.version>1.8</java.version>
-	</properties>
-
 	<dependencies>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
@@ -29,7 +25,6 @@
 		<dependency>
 			<groupId>io.projectreactor</groupId>
 			<artifactId>reactor-core</artifactId>
-			<version>3.0.4.RELEASE</version>
 		</dependency>
 		<dependency>
 			<groupId>commons-io</groupId>

spring-cloud-function-deployer/pom.xml

@@ -15,7 +15,6 @@
 	</parent>
 
 	<properties>
-		<java.version>1.8</java.version>
 		<spring-cloud-deployer-thin.version>1.0.0.BUILD-SNAPSHOT</spring-cloud-deployer-thin.version>
 	</properties>
 
@@ -78,11 +77,6 @@
 
 	<build>
 		<plugins>
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-jar-plugin</artifactId>
-				<version>3.0.0</version>
-			</plugin>
 			<plugin>
 				<groupId>org.springframework.boot</groupId>
 				<artifactId>spring-boot-maven-plugin</artifactId>

spring-cloud-function-samples/spring-cloud-function-sample-compiler/pom.xml

@@ -44,11 +44,6 @@
 
 	<build>
 		<plugins>
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-jar-plugin</artifactId>
-				<version>3.0.0</version>
-			</plugin>
 			<plugin>
 				<groupId>org.springframework.boot</groupId>
 				<artifactId>spring-boot-maven-plugin</artifactId>

spring-cloud-function-samples/spring-cloud-function-sample-pojo/pom.xml

@@ -52,15 +52,9 @@
 
 	<build>
 		<plugins>
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-jar-plugin</artifactId>
-				<version>3.0.0</version>
-			</plugin>
 			<plugin>
 				<groupId>org.springframework.boot</groupId>
 				<artifactId>spring-boot-maven-plugin</artifactId>
-				<version>1.5.1.RELEASE</version>
 				<dependencies>
 					<dependency>
 						<groupId>org.springframework.boot.experimental</groupId>

spring-cloud-function-samples/spring-cloud-function-sample/pom.xml

@@ -22,7 +22,6 @@
 		<spring-cloud-function.version>1.0.0.BUILD-SNAPSHOT</spring-cloud-function.version>
 		<wrapper.version>1.0.0.M2</wrapper.version>
 		<reactor.version>3.0.5.RELEASE</reactor.version>
-		<spring-boot.version>1.5.1.RELEASE</spring-boot.version>
 	</properties>
 
 	<dependencies>
@@ -53,7 +52,6 @@
 			<plugin>
 				<groupId>org.springframework.boot</groupId>
 				<artifactId>spring-boot-maven-plugin</artifactId>
-				<version>${spring-boot.version}</version>
 				<dependencies>
 					<dependency>
 						<groupId>org.springframework.boot.experimental</groupId>

spring-cloud-function-stream/pom.xml

@@ -15,7 +15,6 @@
 	</parent>
 
 	<properties>
-		<java.version>1.8</java.version>
 		<stream.version>1.1.1.BUILD-SNAPSHOT</stream.version>
 	</properties>
 

spring-cloud-function-task/pom.xml

@@ -13,10 +13,6 @@
 		<version>1.0.0.BUILD-SNAPSHOT</version>
 	</parent>
 
-	<properties>
-		<java.version>1.8</java.version>
-	</properties>
-
 	<dependencies>
 		<dependency>
 			<groupId>org.springframework.cloud</groupId>

spring-cloud-function-web/pom.xml

@@ -14,10 +14,6 @@
 		<version>1.0.0.BUILD-SNAPSHOT</version>
 	</parent>
 
-	<properties>
-		<java.version>1.8</java.version>
-	</properties>
-
 	<dependencies>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>