Fixed not defined compiler source and target in build-tools.

build-tools/build-resources/pom.xml

 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-    <modelVersion>4.0.0</modelVersion>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
 
-    <groupId>com.ongres.pgio</groupId>
-    <artifactId>build-resources</artifactId>
-    <version>1.0.0</version>
-    <packaging>jar</packaging>
+	<groupId>com.ongres.pgio</groupId>
+	<artifactId>build-resources</artifactId>
+	<version>1.0.0</version>
+	<packaging>jar</packaging>
 
-    <name>pgio: Build Resources</name>
+	<name>pgio: Build Resources</name>
 
-    <properties>
-        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <checkstyle.skipExec>true</checkstyle.skipExec>
-        <license.skip>true</license.skip>
-    </properties>
+	<properties>
+		<maven.compiler.source>1.8</maven.compiler.source>
+		<maven.compiler.target>1.8</maven.compiler.target>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<checkstyle.skipExec>true</checkstyle.skipExec>
+		<license.skip>true</license.skip>
+	</properties>
 
-    <profiles>
-        <profile>
-            <id>deploy</id> <!-- It must be manually turn on when mvn deploy is executed -->
-            <build>
-                <plugins>
-                    <plugin>
-                        <groupId>org.apache.maven.plugins</groupId>
-                        <artifactId>maven-source-plugin</artifactId>
-                        <version>3.0.1</version>
-                        <executions>
-                            <execution>
-                                <id>attach-sources</id>
-                                <goals>
-                                    <goal>jar-no-fork</goal>
-                                </goals>
-                            </execution>
-                        </executions>
-                    </plugin>
-                    <plugin>
-                        <groupId>org.apache.maven.plugins</groupId>
-                        <artifactId>maven-javadoc-plugin</artifactId>
-                        <version>2.10.4</version>
-                        <configuration>
-                            <failOnError>false</failOnError>
-                        </configuration>
-                        <executions>
-                            <execution>
-                                <id>attach-javadocs</id>
-                                <goals>
-                                    <goal>jar</goal>
-                                </goals>
-                            </execution>
-                        </executions>
-                    </plugin>
-                </plugins>
-            </build>
-        </profile>
-    </profiles>
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-compiler-plugin</artifactId>
+				<version>3.6.1</version>
+				<configuration>
+					<source>${maven.compiler.source}</source>
+					<target>${maven.compiler.target}</target>
+					<compilerArgument>-Xlint:all</compilerArgument>
+					<showDeprecation>true</showDeprecation>
+					<showWarnings>true</showWarnings>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
+
+	<profiles>
+		<profile>
+			<id>deploy</id> <!-- It must be manually turn on when mvn deploy is executed -->
+			<build>
+				<plugins>
+					<plugin>
+						<groupId>org.apache.maven.plugins</groupId>
+						<artifactId>maven-source-plugin</artifactId>
+						<version>3.0.1</version>
+						<executions>
+							<execution>
+								<id>attach-sources</id>
+								<goals>
+									<goal>jar-no-fork</goal>
+								</goals>
+							</execution>
+						</executions>
+					</plugin>
+					<plugin>
+						<groupId>org.apache.maven.plugins</groupId>
+						<artifactId>maven-javadoc-plugin</artifactId>
+						<version>2.10.4</version>
+						<configuration>
+							<failOnError>false</failOnError>
+						</configuration>
+						<executions>
+							<execution>
+								<id>attach-javadocs</id>
+								<goals>
+									<goal>jar</goal>
+								</goals>
+							</execution>
+						</executions>
+					</plugin>
+				</plugins>
+			</build>
+		</profile>
+	</profiles>
 
 </project>