Basic element 'path' must not contain child elements

**Environment**:

- *Jib version:* 3.3.2 and 3.4.2
- *Build tool:* Maven 3.8.6
- *OS:* Windows Server 2016 Standard

**Description of the issue**:
The parsing of the pom configuration seems to depend on some "unexpected feature" in maven.
Using <path> as both a flat element and a parent element seems to not work properly.
Using a single <path> with children breaks the build with error message
_Basic element 'path' must not contain child elements_
By just adding a leading flat <path> element the problem goes away and all runs fine.
For examples of the failing and working setups see below.

**Expected behavior**:
The plugin builds the deliverable containing the stated file.

**Steps to reproduce**:

Use the configuration stated below in a standard jib build.

**`jib-maven-plugin` Configuration**:
```xml

default-cli
package

build



INHERIT
USE_CURRENT_TIMESTAMP

8080





target
/plugin





```

**Log output**:
[ERROR] Failed to execute goal com.google.cloud.tools:jib-maven-plugin:3.3.2:build (default-cli) on project my-nifty-project: Unable to parse configuration of mojo com.google.cloud.tools:jib-maven-plugin:3.3.2:build for parameter path: Basic element 'path' must not contain child elements -> [Help 1]

**Additional Information**:
There is a workaround possible. By adding a flat <path> element the issue does not surface.
```xml



dummy

target
/plugin



```