ADDITIONAL SYSTEM INFORMATION :
OS OSX

java version "15" 2020-09-15
Java(TM) SE Runtime Environment (build 15+36-1562)
Java HotSpot(TM) 64-Bit Server VM (build 15+36-1562, mixed mode, sharing)

javap version 15

A DESCRIPTION OF THE PROBLEM :
Assembly class file include String which has spaces character at last ( e.g. " 123 " ) and last spaces is cut ( e.g. " 123" ) .


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Compile java source.
javac Test.java

public class Test {
    public void test1() {
        String = " 123 ";
    }
}

2. Assembly class file and got Expected Result.
javap -v Test.class

3. And this output of string last spaces is cut.
For example
// 123
// String 123

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Compiled from "Test.java"
public class Test
  minor version: 0
  major version: 59
  flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: #9 // Test
  super_class: #2 // java/lang/Object
  interfaces: 0, fields: 0, methods: 2, attributes: 1
Constant pool:
   #1 = Methodref #2.#3 // java/lang/Object."<init>":()V
   #2 = Class #4 // java/lang/Object
   #3 = NameAndType #5:#6 // "<init>":()V
   #4 = Utf8 java/lang/Object
   #5 = Utf8 <init>
   #6 = Utf8 ()V
   #7 = String #8 // 123
   #8 = Utf8 123
   #9 = Class #10 // Test
  #10 = Utf8 Test
  #11 = Utf8 Code
  #12 = Utf8 LineNumberTable
  #13 = Utf8 test1
  #14 = Utf8 SourceFile
  #15 = Utf8 Test.java
{
  public Test();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0
         1: invokespecial #1 // Method java/lang/Object."<init>":()V
         4: return
      LineNumberTable:
        line 3: 0

  public void test1();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=2, args_size=1
         0: ldc #7 // String 123
         2: astore_1
         3: return
      LineNumberTable:
        line 6: 0
        line 35: 3
}
ACTUAL -
Compiled from "Test.java"
public class Test
  minor version: 0
  major version: 59
  flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: #9 // Test
  super_class: #2 // java/lang/Object
  interfaces: 0, fields: 0, methods: 2, attributes: 1
Constant pool:
   #1 = Methodref #2.#3 // java/lang/Object."<init>":()V
   #2 = Class #4 // java/lang/Object
   #3 = NameAndType #5:#6 // "<init>":()V
   #4 = Utf8 java/lang/Object
   #5 = Utf8 <init>
   #6 = Utf8 ()V
!CHANGED THIS↓ LINE!
   #7 = String #8 // 123 ;
   #8 = Utf8 123
   #9 = Class #10 // Test
  #10 = Utf8 Test
  #11 = Utf8 Code
  #12 = Utf8 LineNumberTable
  #13 = Utf8 test1
  #14 = Utf8 SourceFile
  #15 = Utf8 Test.java
{
  public Test();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0
         1: invokespecial #1 // Method java/lang/Object."<init>":()V
         4: return
      LineNumberTable:
        line 3: 0

  public void test1();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=2, args_size=1
!CHANGED THIS↓ LINE!
         0: ldc #7 // String 123 ;
         2: astore_1
         3: return
      LineNumberTable:
        line 6: 0
        line 35: 3
}

---------- BEGIN SOURCE ----------
public class Test {
    public void test1() {
        String = " 123 ";
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
nothing

But I know that terminal stdout is ignore some spaces character so I tried redirect like this.
javap -v Test.class > out.txt
But also last spaces was cut.

FREQUENCY : always