[java] finish gradle migration (#641)

1. Update documentation
2. Delete pom.xml files
3. Update dependabot configuration
4. Update live-usb-creator

.github/dependabot.yml

@@ -1,6 +1,6 @@
 version: 2
 updates:
-- package-ecosystem: maven
+- package-ecosystem: gradle
   directory: "/java"
   schedule:
     interval: daily

core/CMakeLists.txt

@@ -97,7 +97,7 @@ if (ENABLE_COVERAGE)
     # In terminal 1:
     #   LLVM_PROFILE_FILE="subzero.profraw%c" ./subzero
     # In terminal 2:
-    #   run the GUI test (e.g. java/gui/target/gui-1.0.0-SNAPSHOT-shaded.jar --signtx-test)
+    #   run the GUI test (e.g. java -jar java/gui/build/libs/gui-1.0.0-SNAPSHOT-shaded.jar --signtx-test)
     # Can also run additional tests in terminal 2, e.g. for wallet creation.
     # Back to terminal 1:
     #   ctrl-C to kill the subzero process

docs/regression-testing-howto.md

@@ -24,7 +24,7 @@ instructed in [subzero documentation](./running_without_hsm.md).
 
 ```bash
 # under subzero repository directory root
-./java/gui/target/gui-1.0.0-SNAPSHOT-shaded.jar --signtx-test
+java -jar ./java/gui/build/libs/gui-1.0.0-SNAPSHOT-shaded.jar --signtx-test
 ```
 
 ## How to create test vectors
@@ -52,7 +52,7 @@ Put the following content in `/data/app/subzero/wallets/subzero-1492.wallet`
 
 ```bash
 # under subzero repository directory root
-./java/server/target/server-1.0.0-SNAPSHOT.jar server
+java -jar ./java/server/build/libs/server-1.0.0-SNAPSHOT.jar server
 ```
 
 - Run python script `txsign_testcase_expect_scrypt_gen.py` to generate an
@@ -90,7 +90,7 @@ rm expect_subzero.log
 # Note: The below expects X server to be running. If you are running this
 #       on the dev iso(No X server) then prefix it with xvfb-run <command>. 
 #       That will make awt happy and let the command pass through peacefully!
-/tmp/subzero_expect.sh ./java/gui/target/gui-1.0.0-SNAPSHOT-shaded.jar
+/tmp/subzero_expect.sh ./java/gui/build/libs/gui-1.0.0-SNAPSHOT-shaded.jar
 # 'expect_subzero.log' should show up below
 ls -l expect_subzero.log
 ```

docs/running_without_hsm.md

@@ -6,7 +6,7 @@ not encrypted — Subzero's security model assumes you are using a HSM in your p
 The instructions in this page work with Mac OS X. Linux users can simply skip irrelevant parts. Windows users are
 advised to use a virtualization layer (e.g. Ubuntu inside VirtualBox).
 
-The Core is compiled using _cmake_ and _gcc_. The web server and GUI are built using _maven_ and run with Java.
+The Core is compiled using _cmake_ and _gcc_. The web server and GUI are built using _gradle_ and run with Java.
 Since we don't have a HSM, we'll be using stub classes (included with Subzero) to successfully compile the
 code — HSM-specific steps will then be skipped.
 
@@ -27,9 +27,6 @@ provide additional docker files for running the GUI and web server).
     brew update
     brew cask install java
 
-    # install Maven
-    brew install maven
-
     # note: if Mac OS X gives you a warning about unverified developers, you can go to the
     # Security & Privacy settings and allow the action to take place.
 
@@ -47,7 +44,7 @@ provide additional docker files for running the GUI and web server).
 
     # build the Java code
     cd java
-    mvn package
+    ./gradlew build
 
     # build the C code, using testnet transactions.
     cd ../core
@@ -70,13 +67,13 @@ See also [sample output](core_sample_output.md).
     ./subzero/core/build/subzero
 
     # in a fresh Terminal tab, start the dev/demo server (listens on port 8080)
-    ./subzero/java/server/target/server-1.0.0-SNAPSHOT.jar server
+    java -jar ./subzero/java/server/build/libs/server-1.0.0-SNAPSHOT.jar server
 
     # in a fresh Terminal tab, open http://localhost:8080/.
     open http://localhost:8080/
 
     # start the GUI
-    ./subzero/java/gui/target/gui-1.0.0-SNAPSHOT-shaded.jar
+    java -jar ./subzero/java/build/libs/gui-1.0.0-SNAPSHOT-shaded.jar
 
 Your environment should look as following (from top left, going clockwise): the GUI, a web browser, and a Terminal.