Project won't build with Java 14 (and Gradle 6.1)

[Lysander]

At the current state of the project the build will fail with installed JDK 14 (I use Adopt Open JDK 14).

This seems to be a known Bug of Gradle.
I used this simple workaround described in the comments here.

Just change the file \fpinkotlin\fpinkotlin-parent\gradle\wrapper\gradle-wrapper.properties

distributionBase=GRADLE_USER_HOME
distributionPath=wrapper/dists
distributionUrl=https\://services.gradle.org/distributions/gradle-6.6-bin.zip
#                                                                   ^
#                                                                   6 instead of 1 to upgrade the version of Gradle
zipStoreBase=GRADLE_USER_HOME
zipStorePath=wrapper/dists

After this change the project compiles.