maven-quarkus-plugin fails if base dir is /something/ and project has parent pom
**Describe the bug**
maven-quarkus-plugin fails on build stage if base dir is /something/ and project has parent pom.
It fails with a null pointer exception. 

This is problematic becase the project builds nicelly and then it fails on our pipeline, once we try to build the project inside a container...

Full stack:
`[ERROR] Failed to execute goal io.quarkus:quarkus-maven-plugin:1.4.2.Final:build (default) on project wfm-core: Failed to build quarkus application: NullPointerException -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal io.quarkus:quarkus-maven-plugin:1.4.2.Final:build (default) on project wfm-core: Failed to build quarkus application
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:215)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
Caused by: org.apache.maven.plugin.MojoExecutionException: Failed to build quarkus application
    at io.quarkus.maven.BuildMojo.execute (BuildMojo.java:207)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
Caused by: java.lang.NullPointerException
    at io.quarkus.bootstrap.resolver.maven.workspace.LocalProject.loadRootModel (LocalProject.java:139)
    at io.quarkus.bootstrap.resolver.maven.workspace.LocalProject.loadWorkspace (LocalProject.java:93)
    at io.quarkus.bootstrap.resolver.maven.BootstrapMavenContext.resolveCurrentProject (BootstrapMavenContext.java:245)
    at io.quarkus.bootstrap.resolver.maven.BootstrapMavenContext.<init> (BootstrapMavenContext.java:150)
    at io.quarkus.bootstrap.resolver.maven.MavenArtifactResolver.<init> (MavenArtifactResolver.java:104)
    at io.quarkus.bootstrap.resolver.maven.MavenArtifactResolver.<init> (MavenArtifactResolver.java:53)
    at io.quarkus.bootstrap.resolver.maven.MavenArtifactResolver$Builder.build (MavenArtifactResolver.java:89)
    at io.quarkus.maven.BuildMojo.execute (BuildMojo.java:166)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
` 

If you increase the folder depth to something like /bla/something/, it works.
Looks like this piece of code is not properly protected:

io/quarkus/bootstrap/resolver/maven/workspace/LocalProject.java:139
` pomXml = pomXml.getParent().getParent().resolve(POM_XML);`

This seems to be another, of several bugs, were the .getParent() is not properly handled. Probably a deeper validation on this would be nice. 

**Expected behavior**
Build on any path of the computer.

**Actual behavior**
Build is aborted


**To Reproduce**
Steps to reproduce the behavior:
1. Creata a project with a parent pom coming from the maven repo
2. create a docker file based on docker-maven-base:3.6.3-jdk-11 to build your project and locate the project on a folder like /app 
3. run mvn --settings settings.xml clean install 
4. execute a docker build

**Configuration**
```properties
# Add your application.properties here, if applicable.

```

**Screenshots**
(If applicable, add screenshots to help explain your problem.)

**Environment (please complete the following information):**
 - Output of `uname -a` or `ver`: 
(Container) Linux 7278367b9fa5 5.4.0-28-generic #32-Ubuntu SMP Wed Apr 22 17:40:10 UTC 2020 x86_64 GNU/Linux
--
Apache Maven 3.6.3 (cecedd343002696d0abb50b32b541b8a6ba2883f)
Maven home: /usr/share/maven
Java version: 11.0.6, vendor: Oracle Corporation, runtime: /usr/local/openjdk-11
Default locale: en, platform encoding: UTF-8
OS name: "linux", version: "5.4.0-28-generic", arch: "amd64", family: "unix"


**Additional context**
(Add any other context about the problem here.)

diff --git a/independent-projects/bootstrap/core/src/main/java/io/quarkus/bootstrap/resolver/maven/workspace/LocalProject.java b/independent-projects/bootstrap/core/src/main/java/io/quarkus/bootstrap/resolver/maven/workspace/LocalProject.java
index 24bd7cf98c4..3aa55e21e0d 100644
--- a/independent-projects/bootstrap/core/src/main/java/io/quarkus/bootstrap/resolver/maven/workspace/LocalProject.java
+++ b/independent-projects/bootstrap/core/src/main/java/io/quarkus/bootstrap/resolver/maven/workspace/LocalProject.java
@@ -125,7 +125,7 @@ private static LocalProject load(LocalWorkspace workspace, LocalProject parent,
 
     private static Model loadRootModel(Path pomXml) throws BootstrapException {
         Model model = null;
-        while (Files.exists(pomXml)) {
+        while (pomXml != null && Files.exists(pomXml)) {
             model = readModel(pomXml);
             final Parent parent = model.getParent();
             if (parent != null
@@ -136,7 +136,8 @@ private static Model loadRootModel(Path pomXml) throws BootstrapException {
                     pomXml = pomXml.resolve(POM_XML);
                 }
             } else {
-                pomXml = pomXml.getParent().getParent().resolve(POM_XML);
+                final Path parentDir = pomXml.getParent().getParent();
+                pomXml = parentDir == null ? null : parentDir.resolve(POM_XML);
             }
         }
         return model;
['independent-projects/bootstrap/core/src/main/java/io/quarkus/bootstrap/resolver/maven/workspace/LocalProject.java']