[FLINK-7249] [build] Bump java.version property to 1.8

This closes #4398.

docs/quickstart/java_api_quickstart.md

@@ -31,7 +31,7 @@ Start working on your Flink Java program in a few simple steps.
 
 ## Requirements
 
-The only requirements are working __Maven 3.0.4__ (or higher) and __Java 7.x__ (or higher) installations.
+The only requirements are working __Maven 3.0.4__ (or higher) and __Java 8.x__ (or higher) installations.
 
 ## Create Project
 

docs/quickstart/scala_api_quickstart.md

@@ -119,7 +119,7 @@ Now you can import the project into Eclipse via `File -> Import... -> Existing P
 
 ### Requirements
 
-The only requirements are working __Maven 3.0.4__ (or higher) and __Java 7.x__ (or higher) installations.
+The only requirements are working __Maven 3.0.4__ (or higher) and __Java 8.x__ (or higher) installations.
 
 
 ### Create Project

docs/quickstart/setup_quickstart.md

@@ -30,7 +30,7 @@ Get a Flink example program up and running in a few simple steps.
 
 ## Setup: Download and Start Flink
 
-Flink runs on __Linux, Mac OS X, and Windows__. To be able to run Flink, the only requirement is to have a working __Java 7.x__ (or higher) installation. Windows users, please take a look at the [Flink on Windows]({{ site.baseurl }}/setup/flink_on_windows.html) guide which describes how to run Flink on Windows for local setups.
+Flink runs on __Linux, Mac OS X, and Windows__. To be able to run Flink, the only requirement is to have a working __Java 8.x__ (or higher) installation. Windows users, please take a look at the [Flink on Windows]({{ site.baseurl }}/setup/flink_on_windows.html) guide which describes how to run Flink on Windows for local setups.
 
 You can check the correct installation of Java by issuing the following command:
 

docs/setup/building.md

@@ -31,10 +31,10 @@ This page covers how to build Flink {{ site.version }} from sources.
 
 In order to build Flink you need the source code. Either [download the source of a release]({{ site.download_url }}) or [clone the git repository]({{ site.github_url }}).
 
-In addition you need **Maven 3** and a **JDK** (Java Development Kit). Flink requires **at least Java 7** to build. We recommend using Java 8.
+In addition you need **Maven 3** and a **JDK** (Java Development Kit). Flink requires **at least Java 8** to build.
 
 *NOTE: Maven 3.3.x can build Flink, but will not properly shade away certain dependencies. Maven 3.0.3 creates the libraries properly.
-To build unit tests with Java 8, use Java 8u51 or above to prevent failures in unit tests that use the PowerMock runner.*
+To build unit tests use Java 8u51 or above to prevent failures in unit tests that use the PowerMock runner.*
 
 To clone from git, enter:
 

flink-quickstart/flink-quickstart-java/src/main/resources/archetype-resources/pom.xml

@@ -307,8 +307,8 @@ under the License.
 				<artifactId>maven-compiler-plugin</artifactId>
 				<version>3.1</version>
 				<configuration>
-					<source>1.7</source> <!-- If you want to use Java 8, change this to "1.8" -->
-					<target>1.7</target> <!-- If you want to use Java 8, change this to "1.8" -->
+					<source>1.8</source>
+					<target>1.8</target>
 				</configuration>
 			</plugin>
 		</plugins>

flink-quickstart/flink-quickstart-scala/src/main/resources/archetype-resources/pom.xml

@@ -307,8 +307,8 @@ under the License.
 				<artifactId>maven-compiler-plugin</artifactId>
 				<version>3.1</version>
 				<configuration>
-					<source>1.7</source>
-					<target>1.7</target>
+					<source>1.8</source>
+					<target>1.8</target>
 				</configuration>
 			</plugin>
 			<plugin>

pom.xml

@@ -95,7 +95,7 @@ under the License.
 		<log4j.configuration>log4j-test.properties</log4j.configuration>
 		<guava.version>18.0</guava.version>
 		<akka.version>2.3-custom</akka.version>
-		<java.version>1.7</java.version>
+		<java.version>1.8</java.version>
 		<slf4j.version>1.7.7</slf4j.version>
 		<log4j.version>1.2.17</log4j.version>
 		<!-- Overwrite default values from parent pom.
@@ -750,7 +750,7 @@ under the License.
 		<profile>
 			<id>release</id>
 			<properties>
-				<java.version>1.7</java.version>
+				<java.version>1.8</java.version>
 			</properties>
 			<build>
 				<plugins>