It looks to me like the 3.1 version is currently in beta, and the correct version number for the most recent beta is 3.1.0-beta1. Also, it appears that the maven artifacts are available on JCenter since 3.1.0-alpha2 (https://bintray.com/jmonkeyengine/org.jmonkeyengine/jme3-core/view). The private repository seems to no longer exist.
Given that, I was able to get the following to work:
<?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>
<groupId>com.mycompany</groupId>
<artifactId>jme3-example</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<name>JME3 maven project</name>
<properties>
<jme3.version>3.1.0-beta1</jme3.version>
</properties>
<dependencies>
<dependency>
<groupId>org.jmonkeyengine</groupId>
<artifactId>jme3-core</artifactId>
<version>${jme3.version}</version>
</dependency>
<dependency>
<groupId>org.jmonkeyengine</groupId>
<artifactId>jme3-desktop</artifactId>
<version>${jme3.version}</version>
</dependency>
<dependency>
<groupId>org.jmonkeyengine</groupId>
<artifactId>jme3-lwjgl</artifactId>
<version>${jme3.version}</version>
</dependency>
</dependencies>
<repositories>
<repository>
<id>bintray-jmonkeyengine-org.jmonkeyengine</id>
<name>bintray</name>
<url>http://dl.bintray.com/jmonkeyengine/org.jmonkeyengine</url>
</repository>
</repositories>
</project>
0
solved JMonkeyEngine in Intellij IDEA