Return the value for the nth header field. Returns null if
there are fewer than n fields.  This can be used in conjunction
with getHeaderFieldKey to iterate through all the headers in the message.
1082
public String getHeaderField(int n) {
        try {
            getInputStream();
        } catch (Exception e) {
            return null;
        }
        MessageHeader props = properties;
        return props == null ? null : props.getValue(n);
    }
733059
@Override public final String getHeaderField(int position) {
    try {
      return getHeaders().value(position);
    } catch (IOException e) {
      return null;
    }
  }
84942
private String getSystemField(String fieldName) {
        List<String> values = m_valueMap.get(fieldName);
        return values == null ? null : values.get(0);
    }
1351905
public String getHeaderField(String fieldName) {
        // headers map is null for all regular response calls except when made as a batch request
        if (this.headers == null) {
            if (this.connection != null) {
                return this.connection.getHeaderField(fieldName);
            } else {
                return null;
            }
        } else {
            return this.headers.get(fieldName);
        }
    }
916747
public String getHeaderValue(final String headerName) {
     if (headerName == null) { return null; }
     return request.headers().get(headerName);
   }
1165924
public FieldInfo getField(int iKeyFieldSeq)
    {
        if (iKeyFieldSeq >= m_vKeyFieldList.size())
            return null;
        return (FieldInfo)m_vKeyFieldList.elementAt(iKeyFieldSeq);
    }
49278
static String readAnyField(Object obj, String ... names) {
        try {
            for (String name : names) {
                try {
                    Field field = obj.getClass().getDeclaredField(name);
                    field.setAccessible(true);
                    return (String) field.get(obj);
                } catch (NoSuchFieldException e) {
                    //ignore and try next field...
                }
            }
            return null;
        } catch (IllegalAccessException e) {
            return null;
        }
    }
312349
private static String getHeaderInfo(String name, String headerLine) {
        String[] fields = headerLine.split("[\t ]");
        for (String field : fields) {
            if (field.startsWith(name + "=")) {
                String[] subfields = field.split("=");
                return subfields[1];
            }
        }
        return null;
    }
181576
@Nullable
  public Long getLong(@Nonnull String field) {
    Number number = (Number) get(field);
    return number == null ? null : number.longValue();
  }
1014987
private String getField(int key, String undef) {
    String value = fields[key];
    return value == null ? undef : value;
  }
823373
@Override public final String getHeaderField(String fieldName) {
    try {
      return fieldName == null
          ? StatusLine.get(getResponse().getResponse()).toString()
          : getHeaders().get(fieldName);
    } catch (IOException e) {
      return null;
    }
  }
884336
public Enumeration getFieldValues(String name,String separators)
    {
        return _header.getValues(name,separators);
    }
1345721
def nti(s):
    
    # There are two possible encodings for a number field, see
    # itn() below.
    if s[0] != chr(0o200):
        try:
            n = int(nts(s, "ascii", "strict") or "0", 8)
        except ValueError:
            raise InvalidHeaderError("invalid header")
    else:
        n = 0
        for i in range(len(s) - 1):
            n <<= 8
            n += ord(s[i + 1])
    return n
945380
private @Nullable CodeBlock initialValue(Field field) {
    if (field.isPacked() || field.isRepeated()) {
      return CodeBlock.of("$T.newMutableList()", Internal.class);
    } else if (field.type().isMap()) {
      return CodeBlock.of("$T.newMutableMap()", Internal.class);
    } else {
      return null;
    }
  }
504668
public int
getRcode() {
	int rcode = header.getRcode();
	OPTRecord opt = getOPT();
	if (opt != null)
		rcode += (opt.getExtendedRcode() << 4);
	return rcode;
}
970144
private int findField(String fieldName) {
		int foundIndex = 0;
		for (Field field : fields) {
			if (field != null && fieldName.equals(field.getName())) {
				return foundIndex;
			}

			foundIndex++;
		}

		return -1;
	}
1077137
public String header(String name) {
		final List<String> values = headerList(name);
		if(CollectionUtil.isEmpty(values)) {
			return null;
		}
		return values.get(0);
	}