Added check for empty iterables on bug pattern StringConcatToTextBlock

[CharliePrm88]

While using errorprone on my project:

[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR : 
[INFO] -------------------------------------------------------------
[ERROR] /home/charlie/myproject/mypackage/model/MyClazz.java:[8] error: An unhandled exception was thrown by the Error Prone static analysis plugin.
     Please report this at https://github.com/google/error-prone/issues/new and include the following, as well as a reproducing code sample (if possible):
     error-prone version: 2.44.0
     BugPattern: StringConcatToTextBlock
     Stack Trace:
     java.util.NoSuchElementException
  	at com.google.common.collect.Iterables.getLast(Iterables.java:850)
  	at com.google.errorprone.bugpatterns.StringConcatToTextBlock.matchLiteral(StringConcatToTextBlock.java:101)
  	at com.google.errorprone.scanner.ErrorProneScanner.processMatchers(ErrorProneScanner.java:509)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitLiteral(ErrorProneScanner.java:786)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitLiteral(ErrorProneScanner.java:170)
  	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCLiteral.accept(JCTree.java:2768)
  	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:92)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:74)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:48)
  	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:96)
  	at jdk.compiler/com.sun.source.util.TreeScanner.visitAssignment(TreeScanner.java:677)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitAssignment(ErrorProneScanner.java:566)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitAssignment(ErrorProneScanner.java:170)
  	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCAssign.accept(JCTree.java:2070)
  	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:92)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:74)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:48)
  	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:96)
  	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:111)
  	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:119)
  	at jdk.compiler/com.sun.source.util.TreeScanner.visitAnnotation(TreeScanner.java:1072)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitAnnotation(ErrorProneScanner.java:524)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitAnnotation(ErrorProneScanner.java:170)
  	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCAnnotation.accept(JCTree.java:3052)
  	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:92)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:74)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:48)
  	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:111)
  	at jdk.compiler/com.sun.source.util.TreeScanner.visitModifiers(TreeScanner.java:1057)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitModifiers(ErrorProneScanner.java:838)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitModifiers(ErrorProneScanner.java:170)
  	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCModifiers.accept(JCTree.java:3082)
  	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:92)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:74)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:48)
  	at jdk.compiler/com.sun.source.util.TreeScanner.visitVariable(TreeScanner.java:240)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitVariable(ErrorProneScanner.java:1017)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitVariable(ErrorProneScanner.java:170)
  	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCVariableDecl.accept(JCTree.java:1040)
  	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:92)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:74)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:48)
  	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:96)
  	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:111)
  	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:119)
  	at jdk.compiler/com.sun.source.util.TreeScanner.visitClass(TreeScanner.java:203)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitClass(ErrorProneScanner.java:619)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitClass(ErrorProneScanner.java:170)
  	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:855)
  	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:92)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:74)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:48)
  	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:111)
  	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:119)
  	at jdk.compiler/com.sun.source.util.TreeScanner.visitCompilationUnit(TreeScanner.java:152)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitCompilationUnit(ErrorProneScanner.java:631)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitCompilationUnit(ErrorProneScanner.java:170)
  	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCCompilationUnit.accept(JCTree.java:623)
  	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:66)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:58)
  	at com.google.errorprone.scanner.ErrorProneScannerTransformer.apply(ErrorProneScannerTransformer.java:43)
  	at com.google.errorprone.ErrorProneAnalyzer.finished(ErrorProneAnalyzer.java:231)
  	at jdk.compiler/com.sun.tools.javac.api.MultiTaskListener.finished(MultiTaskListener.java:133)
  	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1436)
  	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1383)
  	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:963)
  	at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:319)
  	at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:178)
  	at jdk.compiler/com.sun.tools.javac.Main.compile(Main.java:64)
  	at jdk.compiler/com.sun.tools.javac.Main.main(Main.java:50)

Class that throw error:

package mypackage.model;

import com.fasterxml.jackson.annotation.JsonFormat;
import lombok.Data;

import java.util.Date;

@Data
public class MyClazz {
    private String someString;
    private String anotherString;
    private String anotherAnotherString;
    private String moreString;
    private AnotherMyClazz someData;
    private AgainAnotherMyClazz someMoreData;
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'")
    private Date firstDate;
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'")
    private Date lastDate;
    private Long oneLong;
}

This PR fix the problem. Cheers.

[cushon]

This is #4918