output: #fixed code
                                  public static String toString(
              final HttpEntity entity, final String defaultCharset) throws IOException, ParseException {
          if (entity == null) {
              throw new IllegalArgumentException("HTTP entity may not be null");
          }
          InputStream instream = entity.getContent();
          if (instream == null) {
              return null;
          }
          try {
              if (entity.getContentLength() > Integer.MAX_VALUE) {
                  throw new IllegalArgumentException("HTTP entity too large to be buffered in memory");
              }
              int i = (int)entity.getContentLength();
              if (i < 0) {
                  i = 4096;
              }
              ContentType contentType = ContentType.getOrDefault(entity);
              String charset = contentType.getCharset();
              if (charset == null) {
                  charset = defaultCharset;
              }
              if (charset == null) {
                  charset = HTTP.DEFAULT_CONTENT_CHARSET;
              }
              Reader reader = new InputStreamReader(instream, charset);
              CharArrayBuffer buffer = new CharArrayBuffer(i);
              char[] tmp = new char[1024];
              int l;
              while((l = reader.read(tmp)) != -1) {
                  buffer.append(tmp, 0, l);
              }
              return buffer.toString();
          } finally {
              instream.close();
          }
      }
input: #vulnerable code 
                                  public static String toString(
              final HttpEntity entity, final String defaultCharset) throws IOException, ParseException {
          if (entity == null) {
              throw new IllegalArgumentException("HTTP entity may not be null");
          }
          InputStream instream = entity.getContent();
          if (instream == null) {
              return null;
          }
          try {
              if (entity.getContentLength() > Integer.MAX_VALUE) {
                  throw new IllegalArgumentException("HTTP entity too large to be buffered in memory");
              }
              int i = (int)entity.getContentLength();
              if (i < 0) {
                  i = 4096;
              }
              String charset = getContentCharSet(entity);
              if (charset == null) {
                  charset = defaultCharset;
              }
              if (charset == null) {
                  charset = HTTP.DEFAULT_CONTENT_CHARSET;
              }
              Reader reader = new InputStreamReader(instream, charset);
              CharArrayBuffer buffer = new CharArrayBuffer(i);
              char[] tmp = new char[1024];
              int l;
              while((l = reader.read(tmp)) != -1) {
                  buffer.append(tmp, 0, l);
              }
              return buffer.toString();
          } finally {
              instream.close();
          }
      } 
                              #location 34 
                              #vulnerability type RESOURCE_LEAK