Add --google-style to select Google Style

--aosp was the only style switch, with no way to select Google style once it had been passed. Wrapper scripts such as Chromium's google-java-format launcher append --aosp unconditionally, leaving projects that format through them no way to opt back into Google Style.

Add a --google-style flag, and allow overriding a previously given style. When both --aosp and --google-style are given, the last one wins.

Fixes #1415

COPYBARA_INTEGRATE_REVIEW=#1415 from hferreiro:no-aosp 0d1c53e
PiperOrigin-RevId: 982482322

Author: hferreiro

core/src/main/java/com/google/googlejavaformat/java/CommandLineOptionsParser.java

@@ -71,6 +71,7 @@ static CommandLineOptions parse(Iterable<String> options) {
             parseRangeSet(linesBuilder, getValue(flag, it, value));
         case "--offset", "-offset" -> optionsBuilder.addOffset(parseInteger(it, flag, value));
         case "--length", "-length" -> optionsBuilder.addLength(parseInteger(it, flag, value));
+        case "--google-style", "-google-style" -> optionsBuilder.aosp(false);
         case "--aosp", "-aosp", "-a" -> optionsBuilder.aosp(true);
         case "--version", "-version", "-v" -> optionsBuilder.version(true);
         case "--help", "-help", "-h" -> optionsBuilder.help(true);

core/src/main/java/com/google/googlejavaformat/java/UsageException.java

@@ -34,6 +34,9 @@ final class UsageException extends Exception {
     Format stdin -> stdout
   --assume-filename, -assume-filename
     File name to use for diagnostics when formatting standard input (default is <stdin>).
+  --google-style, -google-style
+    Use Google Style (2-space indentation). This is the default; if both --aosp and
+    --google-style are given, the last one wins.
   --aosp, -aosp, -a
     Use AOSP style instead of Google Style (4-space indentation).
   --fix-imports-only

core/src/test/java/com/google/googlejavaformat/java/CommandLineOptionsParserTest.java

@@ -77,6 +77,20 @@ public void aosp() {
     assertThat(CommandLineOptionsParser.parse(Arrays.asList("-aosp")).aosp()).isTrue();
   }
 
+  @Test
+  public void googleStyle() {
+    assertThat(CommandLineOptionsParser.parse(Arrays.asList("--google-style")).aosp()).isFalse();
+    assertThat(CommandLineOptionsParser.parse(Arrays.asList("-google-style")).aosp()).isFalse();
+  }
+
+  @Test
+  public void lastStyleWins() {
+    assertThat(CommandLineOptionsParser.parse(Arrays.asList("--aosp", "--google-style")).aosp())
+        .isFalse();
+    assertThat(CommandLineOptionsParser.parse(Arrays.asList("--google-style", "--aosp")).aosp())
+        .isTrue();
+  }
+
   @Test
   public void help() {
     assertThat(CommandLineOptionsParser.parse(Arrays.asList("-help")).help()).isTrue();