Clean up Java 6 leftover

See gh-10367

README.adoc

@@ -95,8 +95,7 @@ requests. If you want to raise an issue, please follow the recommendations below
 You don't need to build from source to use Spring Boot (binaries in
 http://repo.spring.io[repo.spring.io]), but if you want to try out the latest and
 greatest, Spring Boot can be easily built with the
-https://github.com/takari/maven-wrapper[maven wrapper]. You also need JDK 1.8 (although
-Boot applications can run on Java 1.6).
+https://github.com/takari/maven-wrapper[maven wrapper]. You also need JDK 1.8.
 
 [indent=0]
 ----

eclipse/org.eclipse.jdt.core.prefs

@@ -11,9 +11,9 @@ org.eclipse.jdt.core.codeComplete.staticFinalFieldPrefixes=
 org.eclipse.jdt.core.codeComplete.staticFinalFieldSuffixes=
 org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
 org.eclipse.jdt.core.compiler.codegen.methodParameters=generate
-org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.6
+org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.8
 org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
-org.eclipse.jdt.core.compiler.compliance=1.6
+org.eclipse.jdt.core.compiler.compliance=1.8
 org.eclipse.jdt.core.compiler.debug.lineNumber=generate
 org.eclipse.jdt.core.compiler.debug.localVariable=generate
 org.eclipse.jdt.core.compiler.debug.sourceFile=generate
@@ -104,7 +104,7 @@ org.eclipse.jdt.core.compiler.problem.unusedPrivateMember=warning
 org.eclipse.jdt.core.compiler.problem.unusedWarningToken=warning
 org.eclipse.jdt.core.compiler.problem.varargsArgumentNeedCast=warning
 org.eclipse.jdt.core.compiler.processAnnotations=disabled
-org.eclipse.jdt.core.compiler.source=1.6
+org.eclipse.jdt.core.compiler.source=1.8
 org.eclipse.jdt.core.formatter.align_type_members_on_columns=false
 org.eclipse.jdt.core.formatter.alignment_for_arguments_in_allocation_expression=16
 org.eclipse.jdt.core.formatter.alignment_for_arguments_in_annotation=0

spring-boot-cli/src/main/content/INSTALL.txt

@@ -7,7 +7,7 @@ in order to complete your installation.
 
 Prerequisites
 -------------
-Spring Boot CLI requires Java JDK v1.6 or above in order to run. Groovy v${groovy.version}
+Spring Boot CLI requires Java JDK v1.8 or above in order to run. Groovy v${groovy.version}
 is packaged as part of this distribution, and therefore does not need to be installed (any
 existing Groovy installation is ignored).
 

spring-boot-parent/pom.xml

@@ -736,8 +736,6 @@
 					<plugin>
 						<!-- Up the compiler version so the correct execution environment is
 							used -->
-						<!-- The profile is only active in eclipse so we still target 1.6 on
-							the command line -->
 						<groupId>org.apache.maven.plugins</groupId>
 						<artifactId>maven-compiler-plugin</artifactId>
 						<configuration>

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

@@ -15,8 +15,8 @@
 				<artifactId>maven-compiler-plugin</artifactId>
 				<version>@maven-compiler-plugin.version@</version>
 				<configuration>
-					<source>1.6</source>
-					<target>1.6</target>
+					<source>1.8</source>
+					<target>1.8</target>
 				</configuration>
 			</plugin>
 			<plugin>

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

@@ -15,8 +15,8 @@
 				<artifactId>maven-compiler-plugin</artifactId>
 				<version>@maven-compiler-plugin.version@</version>
 				<configuration>
-					<source>1.6</source>
-					<target>1.6</target>
+					<source>1.8</source>
+					<target>1.8</target>
 				</configuration>
 			</plugin>
 			<plugin>

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

@@ -15,8 +15,8 @@
 				<artifactId>maven-compiler-plugin</artifactId>
 				<version>@maven-compiler-plugin.version@</version>
 				<configuration>
-					<source>1.6</source>
-					<target>1.6</target>
+					<source>1.8</source>
+					<target>1.8</target>
 				</configuration>
 			</plugin>
 			<plugin>

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

@@ -15,8 +15,8 @@
 				<artifactId>maven-compiler-plugin</artifactId>
 				<version>@maven-compiler-plugin.version@</version>
 				<configuration>
-					<source>1.6</source>
-					<target>1.6</target>
+					<source>1.8</source>
+					<target>1.8</target>
 				</configuration>
 			</plugin>
 			<plugin>

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

@@ -16,8 +16,8 @@
 				<artifactId>maven-compiler-plugin</artifactId>
 				<version>@maven-compiler-plugin.version@</version>
 				<configuration>
-					<source>1.6</source>
-					<target>1.6</target>
+					<source>1.8</source>
+					<target>1.8</target>
 				</configuration>
 			</plugin>
 			<plugin>