[prone] fix warning `StaticImport`, `NonStaticImport`

Following the build, `StaticImport` has the potential to remove a lot of warnings, improving focus on the truly important stuff by moving the class context into `oblivion` using the static import.

These would again reduce the log significantly, making more space for better clarity:

- **StaticImport**
- https://error-prone.picnic.tech/bugpatterns/StaticImport/
- **NonStaticImport**
- https://error-prone.picnic.tech/bugpatterns/NonStaticImport/
- **UnnecessaryDefaultInEnumSwitch**
- https://error-prone.picnic.tech/bugpatterns/UnnecessaryDefaultInEnumSwitch/
- https://github.com/diffplug/spotless/pull/2702

```
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'requireNonNull(elements);'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/LibPreconditions.java:27: Note: [StaticImport] Identifier should be statically imported
Objects.requireNonNull(element);
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'requireNonNull(element);'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/MoreIterables.java:43: Note: [StaticImport] Identifier should be statically imported
return toSortedSet(raw, Comparator.naturalOrder());
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'return toSortedSet(raw, naturalOrder());'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/FileSignature.java:106: Note: [LexicographicalAnnotationListing] Sort annotations lexicographically where possible
@SuppressFBWarnings("SE_TRANSIENT_FIELD_NOT_RESTORED")
^
(see https://error-prone.picnic.tech/bugpatterns/LexicographicalAnnotationListing)
Did you mean '@Nullable'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/FileSignature.java:137: Note: [StaticImport] Identifier should be statically imported
return Collections.unmodifiableList(files);
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'return unmodifiableList(files);'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/FormatterStepEqualityOnStateSerialization.java:63: warning: [EqualsGetClass] Prefer instanceof to getClass when implementing Object#equals.
public boolean equals(Object o) {
^
(see https://errorprone.info/bugpattern/EqualsGetClass)
Did you mean 'if (!(o instanceof FormatterStepEqualityOnStateSerialization)) {'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/FormatterStepSerializationRoundtrip.java:125: Note: [StaticImport] Identifier should be statically imported
return original != null ? original : Objects.requireNonNull(cleaned, "how is clean null if this has been serialized?");
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'return original != null ? original : requireNonNull(cleaned, "how is clean null if this has been serialized?");'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/FormatterStepSerializationRoundtrip.java:129: warning: [EqualsGetClass] Prefer instanceof to getClass when implementing Object#equals.
public boolean equals(Object o) {
^
(see https://errorprone.info/bugpattern/EqualsGetClass)
Did you mean 'if (!(o instanceof HackClone)) {'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/Formatter.java:47: Note: [StaticImport] Identifier should be statically imported
this.lineEndingsPolicy = Objects.requireNonNull(lineEndingsPolicy, "lineEndingsPolicy");
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'this.lineEndingsPolicy = requireNonNull(lineEndingsPolicy, "lineEndingsPolicy");'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/Formatter.java:48: Note: [StaticImport] Identifier should be statically imported
this.encoding = Objects.requireNonNull(encoding, "encoding");
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'this.encoding = requireNonNull(encoding, "encoding");'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/Formatter.java:119: Note: [StaticImport] Identifier should be statically imported
Objects.requireNonNull(unix, "unix");
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'requireNonNull(unix, "unix");'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/Formatter.java:120: Note: [StaticImport] Identifier should be statically imported
Objects.requireNonNull(file, "file");
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'requireNonNull(file, "file");'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/Formatter.java:152: warning: [Slf4jLoggerDeclaration] SLF4J logger declarations should follow established best-practices
private static final Logger LOGGER = LoggerFactory.getLogger(Formatter.class);
^
(see https://error-prone.picnic.tech/bugpatterns/Slf4jLoggerDeclaration)
Did you mean 'LOG.error("Step '{}' found problem in '{}':\n{}", formatter.getSteps().get(i).getName(), file.getName(), exception.getMessage(), exception);'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/Formatter.java:165: Note: [StaticImport] Identifier should be statically imported
Objects.requireNonNull(unix, "unix");
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'requireNonNull(unix, "unix");'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/Formatter.java:166: Note: [StaticImport] Identifier should be statically imported
Objects.requireNonNull(file, "file");
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'requireNonNull(file, "file");'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/Formatter.java:223: Note: [LexicographicalAnnotationListing] Sort annotations lexicographically where possible
@SuppressWarnings("rawtypes")
^
(see https://error-prone.picnic.tech/bugpatterns/LexicographicalAnnotationListing)
Did you mean '@Override'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/Formatter.java:242: warning: [ReferenceEquality] Comparison using reference equality instead of value equality
if (file == Formatter.NO_FILE_SENTINEL) {
^
(see https://errorprone.info/bugpattern/ReferenceEquality)
Did you mean 'if (Objects.equals(file, Formatter.NO_FILE_SENTINEL)) {' or 'if (file.equals(Formatter.NO_FILE_SENTINEL)) {'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/ValuePerStep.java:36: Note: [LexicographicalAnnotationListing] Sort annotations lexicographically where possible
@Override
^
(see https://error-prone.picnic.tech/bugpatterns/LexicographicalAnnotationListing)
Did you mean '@Nullable'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java:38: warning: [InlineMeSuggester] This deprecated API looks inlineable. If you'd like the body of the API to be automatically inlined to its callers, please annotate it with @InlineMe. NOTE: the suggested fix makes the method final if it was not already.
public Policy createPolicy() {
^
(see https://errorprone.info/bugpattern/InlineMeSuggester)
Did you mean '@InlineMe(replacement = "super.createPolicy()")'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java:37: Note: [LexicographicalAnnotationListing] Sort annotations lexicographically where possible
@Override @Deprecated
^
(see https://error-prone.picnic.tech/bugpatterns/LexicographicalAnnotationListing)
Did you mean '@Deprecated @Override'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java:46: warning: [InlineMeSuggester] This deprecated API looks inlineable. If you'd like the body of the API to be automatically inlined to its callers, please annotate it with @InlineMe. NOTE: the suggested fix makes the method final if it was not already.
public Policy createPolicy() {
^
(see https://errorprone.info/bugpattern/InlineMeSuggester)
Did you mean '@InlineMe(replacement = "super.createPolicy()")'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java:45: Note: [LexicographicalAnnotationListing] Sort annotations lexicographically where possible
@Override @Deprecated
^
(see https://error-prone.picnic.tech/bugpatterns/LexicographicalAnnotationListing)
Did you mean '@Deprecated @Override'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java:64: Note: [StaticImport] Identifier should be statically imported
Objects.requireNonNull(projectDir, "projectDir");
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'requireNonNull(projectDir, "projectDir");'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java:65: Note: [StaticImport] Identifier should be statically imported
Objects.requireNonNull(toFormat, "toFormat");
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'requireNonNull(toFormat, "toFormat");'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java:86: warning: [StatementSwitchToExpressionSwitch] This statement switch can be converted to a new-style arrow switch
switch (this) {
^
(see https://errorprone.info/bugpattern/StatementSwitchToExpressionSwitch)
Did you mean 'return switch (this) {' or 'switch (this) {'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java:117: Note: [StaticImport] Identifier should be statically imported
try (Reader reader = new FileReader(file, StandardCharsets.US_ASCII)) {
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'try (Reader reader = new FileReader(file, US_ASCII)) {'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java:160: warning: [MissingSummary] A summary fragment is required; consider using the value of the @see block as a summary fragment instead.
* @deprecated Using the system-native line endings to detect the windows operating system has turned out
^
(see https://google.github.io/styleguide/javaguide.html#s7.2-summary-fragment)
Did you mean '*See {@link FileSignature#machineIsWin()}.'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java:172: warning: [StatementSwitchToExpressionSwitch] This statement switch can be converted to a new-style arrow switch
switch (this) {
^
(see https://errorprone.info/bugpattern/StatementSwitchToExpressionSwitch)
Did you mean 'return switch (this) {' or 'switch (this) {'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java:189: Note: [StaticImport] Identifier should be statically imported
Objects.requireNonNull(file);
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'requireNonNull(file);'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/ProcessRunner.java:226: Note: [StaticImport] Identifier should be statically imported
return new String(stdOut, StandardCharsets.UTF_8);
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'return new String(stdOut, UTF_8);'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/ProcessRunner.java:230: Note: [StaticImport] Identifier should be statically imported
return new String(stdErr, StandardCharsets.UTF_8);
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)
Did you mean 'return new String(stdErr, UTF_8);'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/ProcessRunner.java:263: warning: [StringSplitter] String.split(String) has surprising behavior
String[] lines = string.replace("\r", "").split("\n");
^
(see https://errorprone.info/bugpattern/StringSplitter)
Did you mean 'List lines = Splitter.on('\n').splitToList(string.replace("\r", ""));'?
/Users/vincent.potucek/IdeaProjects/spotless/lib/src/main/java/com/diffplug/spotless/go/GofmtFormatStep.java:107: Note: [StaticImport] Identifier should be statically imported
this.exe = Objects.requireNonNull(goExecutable);
^
(see https://error-prone.picnic.tech/bugpatterns/StaticImport)

```